There are no radio signals. Radio doesn't work very well underwater.

They probably don't have subspace communications but they check.

No subspace either!

The ship takes a lot of data and circles the planet for a local day, mapping the light density.

Then it leaves.

Deep underwater, in the shining cities, the handful of mermaids fascinated enough by the night sky to make a study of astronomy despite the difficulties posed by the intervening surface of the water are going bananas over the latest readings from their instruments.

After three days, several ships approach the planet, and one slowly comes in for a landing.

A few hours later, the shore the ship is resting on is approached by half-a-dozen person-sized figures.

From the waist up, they're shaped mostly like Amentans--two arms, ten fingers, a head the right shape and size. From the waist down, powerful tails propel them rapidly through the water. They're covered from head to tail with shimmering scales, and in place of hair, undulous fins stretch from the tops of their heads to the smalls of their backs. 

Two of them are carrying a box between them. One of them has four babies attached to their torso.

The Amentans have used these hours to determine that the atmosphere is safe to breathe, set up tents and various observational equipment, and start assembling their sea probe, but they haven't yet released the sea probe.

When the merpeople approach, the Amentans assume teeth-hiding smiles and open, empty-handed body language.

The mermaids stop several yards from shore and set up camp on a shelf of rock. They open the box and pull out a tent-like thing and several of what resemble space suits. While the others are setting up, the two that were carrying the box don suits and swim the rest of the way to shore. They crawl out of the water and mirror the Amentans' open-handed gesture.

"Hello!" says an Amentan with blue hair (there are also two greys, a couple greens, and a yellow visible; there are several purples in the background).

The mermaid on the left presses two buttons on the front of its suit, and then a crooning like whalesong emits from the suit. 

They've got a recorder going and play it back.

The mermaids are excited about this! They make a combination of crooning and clicking noises at each other, then each one points at themself and emits a set of phonemes that are presumably their names. 

The Amentans play that back too, pointing the speaker at the correct mermaid, and then introduce themselves!

The mermaids are very happy to play the "try to teach each other our languages like one of us is a Feanor" game!

So are the Amentans! Mostly the green ones. They can't pronounce the whalesong but they can get it snipped into bits and chain them together on their computers.

After a while, three of the other mermaids suit up and come out to talk to the Amentans. The last adult hangs out in the shallows, watching the babies as they excitedly interact with the concept of the ocean having a surface. 

The Amentans did not bring any kids, but the merbabies are cute. They take pictures and show them to the merfolk.

The merfolk are charmed by the aliens taking baby pictures! 

One of the merfolk expresses, via a combination of established words and images projected from the suit onto the sand, that if any of the aliens wanted to wade out into the shallows and hold an underwater baby that that would be a great photo op. 

One of the greys is brave enough to do this! Out he wades. Which baby wants to be held?

A silvery baby with blue-green streaks on its sides and an especially fluffy dorsal fin swims up to him, big eyes curious and tiny fingers grasping. 

"Awwww!" says the grey, and he scoops the baby without removing it from the water.

The baby snuggles up, attaching itself to the grey's chest with some kind of suction-cup-like thing on its chest, then pats the grey curiously. It warbles in gleeful interest. 

The other three babies swarm around the grey's legs, curious what these weird twinned tail things are. 

The grey wiggles his toes at the babies and pets the one on his chest gently.

The adult mermaid swims over and smiles and withdraws a handful of soft grey stuff out of a pouch at their waist. The three unattached babies swarm her, and she feeds them, giggling, offering the grey some to feed to the attached baby. 

He feeds the baby! The greens take so many pictures.

Mermaids are presumably also taking many pictures, but since their cameras are built into their suits this is less visible. 

Fed babies curl up and go to sleep on their attached adults. The mermaid in the water conveys through translation by their land-suited compatriots that when the grey wants to go back on land the baby can in fact be detached safely. 

The grey eventually does detach the baby and pat it and send it off to its parent.

The parent carefully attaches the baby to their tail and waves at the grey as they leave before swimming back to camp. 

Eventually, between the two groups, they're sure to get enough vocabulary accumulated for machine translation to start working reasonably well sooner than later. 

Machine translation is much better at writing than at sound, especially sound with phonemes it wasn't trained on; what have they got in writing?

Their suit projectors can totally do writing! They have a lot of random books in their suit computers! 

That's great! They can feed those into their own computers and get written machine translation working on it, with some bugs since they don't have anybody legitimately fluent in both to push patches.

"We are delighted to meet you! We don't think our name for our species can be rendered in your language," writes their computer.

"We are also delighted to meet you! We have devised a method for rendering our phonemes into your writing; it isn't exact, but by representing our hard phonemes as some of your consonants and our soft phonemes as vowels we think we have devised a way to transfer our speech into yours with better-than-random correlation! We are, then, the Keoatiek."

"We are the Amentans! The green handling the linguistics will say that aloud now."

"Amentans," says the green.

The mermaid computers record this. "We're probably going to call you aliens or land-walkers, at least for a while," the lead mermaid admits. "We can't pronounce that very well." 

"That's okay. Keoatiek isn't very easy to say either. We have stories about imaginary creatures that look sort of like you called 'merpeople', which means people who live in the sea, and we might sometimes call you that."

"That sounds totally reasonable!" 

One of the other mermaids points to an Amentan's hair and says, "The colorful things on your heads, are they hats or part of your body?"

"They're parts of our body! The colors signal which caste we're part of."

The mermaids confer briefly. "Caste? That's not translating very well."

"Amentans have six castes. We inherit them from our parents, and they let us know what sorts of jobs we will be good at. It's more complicated than that, of course. The caste we didn't bring an example of is orange. The ones we have here are blue, grey, green, yellow, and purple."

"Oh! That must complicate adoption a lot, but I think I see. It would make eugenics a lot more precise, too, wouldn't it."

"It does help with eugenics! We don't have a lot of adoption but when we do it's within castes."

"...You don't have a lot of adoption?" 

This seems to concern the mermaids. Like, a lot. 

"Most people prefer to keep their own children and arrange to be able to do that. When there are children whose parents die usually their family members will take them in."

There is more discussion among the mermaids. 

"How large are your clutches?" the leader finally asks. 

"- we usually have one baby at a time, sometimes two."

"Oh. Yes, that would result in much less adoption! We lay clutches of hundreds of eggs at a time, and we usually can't find adoptive parents for all the ones the birth mother doesn't take home."

"Do many of you lay eggs?"

"--We're not biological hermaphrodites, if that's what you mean, and we sterilize for all major crimes, and have a number of compensated voluntary sterilization programs, so less than half of everyone who survives to adulthood has biological children at at some point."

"That would still multiply your population - enormously - every generation," say the Amentans, after some frantic whispered discussion.

"...It doesn't seem terribly enormous to us--we still have a lot of sea floor and other rock formations to build on--but we're working on slowing it. That's, ah, not our area of expertise, though, we're five astronomers and an aerobiologist."

"Amentans cannot have more than fifteen pregnancies per female in a lifetime without doing some unpleasant hormonal adjustments," the Amentans say. "We had a period in our history when that was still too many. It was very important to our history to invent birth control and enforce its use to keep our population stable."

"Oh, we almost never have females go through multiple pregnancies, unless the first one ended in miscarriage."

They don't reply for a while, reading over old translations and muttering amongst themselves, then say:

"How many children usually survive?"

The mermaids look things up. 

"The latest figures on my suit's archives show an average of 71.6%," one of them reports. 

"We want to help you," say the Amentans. "Have you already tried things to get smaller clutches?"

"Oh, yes--that's the strongest thing they eugenically select for, you can actually get a sentence of sterilization commuted if you have few enough biological siblings--we try reductive abortions, sometimes, but that often leads the body to flush the whole batch so not everyone is willing to do it." 

"I have a cousin in pharmaceutical research who says they've been working on drugs to reduce numbers at conception for ages," one chimes in, "but they've been stuck in animal testing for decades because they keep having detrimental side-effects on the children." 

"We'd like to send everything you have on that whole area of research home for our scientists to look at," say the Amentans.

This sparks some furious discussion between the mermaids for a few minutes before they come to a consensus and the leader says, "We brought six landsuits even though there were babies along and someone was going to look after them; you can have the spare. If one of you wants to come into the water so Aoaekikek can show you how to operate the suitboard computer you should be able to access the archives that way. Getting more specialized information will take longer since we'll have to send someone back to get it."

"What we really need to do is to copy all of it to our computers. We can send for a bigger team."

"How long will it take your bigger team to get here?"

"It takes three days for a round trip between here and Amenta, but it might take longer for the team to prepare."

"It takes less than three days for a round trip to the nearest city." 

"Do you have a way to convert your files into files our computers can use in your city?"

"No, but we have lots more files in our city."

"We noticed that you do not send signals we could detect in the frequency range from around twenty thousand times per second to around three hundred billion times per second. Does this mean you must travel to your city to get the files or do you have another way?"

"From the city, we can get files from anywhere on the planet, but we don't have Internet out here. We can start laying cables to get Internet up to the surface as soon as we convince the right people it's a good idea, but free-floating cable tends to cause problems."

"We can bring the machines that send signals in those frequencies, and the signals can travel through air, so with the right equipment we will be able to get files anywhere once there is something sharing the files up out of the water."

"Agreed." 

One of the mermaids crawls back into the water, removes their landsuit, folds it up, and then starts swimming back in the directions the mermaids came from. He's out of view shortly. 

"With any luck, the files in Kekaoke's suit will be enough to convince the government we're not lying about first contact." 

"We weren't observed coming in by enough people to make it obvious we were really here?"

The leader gestures at the choppy surface of the water. "Seeing things above the water is hard, from down where the city is. We're here because we had instruments for observing the stars which caught your ship."

"We're happy to offer any proof you'd find useful. We have some spare objects that might be interestingly different and survive the water."

"That might help!"

They provide the merpeople with a pair of pants, a pair of shoes, a scrunchie, somebody's hard copy of a photo of their family (that they assure the merfolk can be printed out again and replaced) in a plastic bag, a can of beans that will not survive unlimited water pressure but should be okay for a ways, and an abacus they brought to try to start from math in case the aliens were less easy to talk to than the merfolk turned out to be.

A second mermaid swims off to deliver these items to the first and/or the relevant authorities. 

The aerobiologist would like to know things about Amentan biology!

Amentans are from a planet with long years! They can have kids in the spring, once per year, but usually have fewer (in the country these Amentans represent, you buy permission to have one from the government, which replaces taxes). They take four of their years to grow up, and live to be forty, but can't have kids once they hit twenty. They have six castes, which aren't perfectly correlated with natural hair color but it's pretty close. They have bones and muscles and skin and membranes and eyes and fingernails and brains and stuff! Their xenobio guy did study some Amentan biology before tracking into xenobio so he knows things to tell them.

Mermaids have years about a quarter of the length of Amenta's and can reproduce year-round, although very small merchildren emit a chemical that prevents their mothers from conceiving more while caring for them. They grow up slightly slower, taking twenty of their years to become a full adult, but are fertile younger than that. In modern times everyone is fitted with a removable birth control device when they hit the age at which people start to become fertile. Scale color and pattern are correlated with where your ancestors came from, but not aptitudes as far as anyone knows. They also have bones and muscles and membranes and eyes and brains! They sorta have skin. They don't have extruded keratin to make hair and fingernails. Why is hair a thing?

Many animals related to Amentans have hair all over their bodies at about the same length to keep them warm; in Amentans it's very fine and sparse over most of the body and only substantial on the scalp and eyebrows (and eyelashes). They're actually not sure why scalp hair persisted originally - it might have stuck around to retain ancestor species' social grooming habits while otherwise disappearing, and lasted long enough to acquire cosmetic and social significance. Eyebrows and eyelashes both keep stuff out of their eyes, which are delicate and must be open to see.

That makes sense. Mermaids solve the eye thing with transparent membranes over their eyes. 

Giving birth to a fully-formed baby who is not in an egg sounds uncomfortable.

In the modern day they have good enough painkillers, but yes, it is uncomfortable, sometimes even a little bloody. The moms recover very fast though.

That's good! 

Amenta must have such different stars. 

They DO! Would they like to see pictures of Amentan constellations?!

YES!!!!!!!!!! 

(These are such green mermaids.)

The greens are delighted. They bring up Amentan constellation images.

The mermaids are so excited!!! Is their sun visible from Amenta? If so, which one is it?

Their sun is visible from Amenta! It's this one.

Oooh!

The mermaids do some calculations on their suit computers. So that means that...they project an image of the night sky from this planet...that means that this star is Amenta's sun, right? 

That's right!

That is so cool. 

Mermaids and greens continue to green at each other for several hours, until a group of several mermaids is spotted swimming in this direction. 

"Are those friends of yours?"

"Oh! Yes! That's Councilor Aoieaaue, I voted for them last election cycle," the mermaid says, pointing at one near the front of the formation. "It looks like they were believed!"

"What do councilors do?"

"City councilors like Councilor Aoieaaue run cities. Provincial councilors run provinces, and the national councilors run the country."

"How many countries are there on this planet?"

"Ninety-seven."

"Are you on good terms with them?"

"No one's currently at war, but there are some I wouldn't say we're friendly with."

"I'm glad we didn't land in the middle of a war! Amenta is at peace now too."

"Wars are terrible," the mermaid agreed. "I watched a documentary that included footage taken by a war correspondent, once, and I couldn't sleep without nightmares for ages."

"We've had some in living memory, but things were calm when we invented faster than light travel, and have stayed that way since!"

"That's good. I think there are still people alive who remember the last war, I'm just not one of them, and glad of it." 

The rest of the mermaids make it to the scientists' camp and start setting other things up, one of which being a big boxy piece of equipment of some kind. Several of the mermaids, including Councilor Aoieaaue, begin suiting up to come on land. Others fuss over setup and the boxy equipment. 

"The next time we have an equipment run we'll get diving equipment so we can come to you. It looks uncomfortable for you to be up here."

"It isn't entirely comfortable," the councilor admits, "but the ability to make contact with a new civilization from another planet more than makes up for it." The councilor turns to confer with one of the other mermaids, who hands them a box. "As a gesture of friendship, I am authorized to present to you as a gift from our people to yours, the mosaic Tears Conquered, an archetypical example of the work of Kikikea."

The xenobio green opens the box.

"Many Amentans enjoy going underwater recreationally. With the right equipment we'll be comfortable," the Amentans assure the merpeople. "We are honored by your gift."

The mosaic depicts a mermaid with an expression of disbelieving joy on her face, surrounded by a swarm of six babies. In the background, other mermaids, some in pairs, some alone, are greeting a swarm of infants rising from a depression in the floor. 

"That seems most efficient, then. In the meanwhile, my assistants are setting up a temporary transmitter station, so that we will be able to communicate with the wider world until more permanent cables have been set up."

The Amentans take pictures of the mosaic.

"If it would be more convenient for us to land somewhere else, we can also do that," the Amentans say. "What is this piece about?"

"It was created in the early days of the modern creche system," the councilor explains. "Before then, it was common for nearly all of one's offspring to die, but since then, the majority have been adopted out to other families. It revolutionized our civilization. The mermaid in the foreground is the biological mother, and the other adults are adoptive parents." 

"That must save you so much grief," say the Amentans. "We hope we'll be able to help with the rest of it somehow, but we don't know how much a fresh look at the problem will help given that we don't have much background in your medicine."

"So much," the councilor agreed. "Even before the modern creche was invented, just having children indoors with medical professionals who could euthanize the extras instead of leaving them to die of exposure--" they broke off, shuddering. "We're all incredibly grateful for modern civilization." 

"We found our own population grief much alleviated by the prospect of settling more planets," say the Amentans. "Since you prefer water and we prefer land it seems not impossible in principle that we could one day share planets, but because your problem is lack of parents and not lack of living space, that can't be the whole solution."

"Indeed," the councilor agrees, "although those of us whose professions involve keeping an eye to the future were certainly starting to worry about what would happen in as many generations as it takes to start running out of room."

"Our planet has a bit more land area than this one but not by very much. There are about thirteen billion Amentans, but that will rise now that we have room to spread out."

"Oh? I would have expected terrestrial sentient life to have evolved on a planet with much more land than us, I admit I'm a bit surprised." 

"We don't yet know which is more common! You're the first extramentan sapients we've found. Other planets with any life at all mostly stop with microscopic organisms and things like moss and coral."

"How peculiar. Although perhaps not, considering how long it took more complex life to evolve." 

"It's early in our space exploration program."

Nod. "We're very excited. Friendly aliens are something parts of our civilization have been dreaming of for as long as there's been science fiction."

"Do you have anything like a space program in the works, or has starting underwater been too much of a disadvantage there?"

"The latter, unfortunately."

"We're so glad we found you."

"We're so glad to hear it! I hope that this may become the start of a long and beautiful relationship between our two species."

"We hope so too!"

There is some muttering amongst the Amentans. The grey who did the photo op with the babies nips off to take a shower. "Is this a good time for a question that might be delicate?"

"I don't see why not."

"We're wondering how you keep yourselves clean when you're always in the same broader body of water."

"Oh, we're very careful about that. Bodies are sealed and removed to uninhabited areas extremely quickly, and our waste disposal systems are completely watertight; unless something goes incredibly wrong no bodily waste touches the general water. Wars have been started over shallower civilizations accidentally dropping a corpse into their deeper neighbors." 

The Amentans relax considerably. Someone calls something over to the grey in the shower. "Do you have a particular sort of person who handles the waste systems and body disposal?"

"Engineers deal with the waste systems and hazmat teams deal with dead bodies and waste system failures--although the latter are extremely rare." 

"Do they have a way of thoroughly cleaning themselves when they're done with work for the day?"

"...They shouldn't need to unless something goes wrong with their hazmat suits, but yes, of course. Anyone exposed to foul water is thoroughly cleaned and checked thoroughly for infection." 

"That's good to hear. We used to have a caste dedicated to dealing with unclean things but with recent technology it was possible to transition them into other castes and have enough barriers between workers and their work that purples can do the same things."

"You had a caste for that? That sounds extremely unfortunate for them. Before doing foul water cleanup could be done safely with hazmat suits it was a job for condemned criminals." 

"That seems like a reasonable setup! It's not the one our ancestors settled on and it was difficult to break out of the equilibrium once it was in place. Now all of the reds have chosen new castes and integrated into them."

"I'm very glad to hear that. It seems like a transition that would benefit everyone." 

"We're glad we've finally managed it."

"It sounds like it must have been difficult. We commend you."

"Thank you. Is there anything else we should bring back from Amenta the next time one of our ships make a trip that hasn't come up yet? People back home are eager for news and one of our ships in orbit is getting ready to depart to tell them what's going on."

"We would love to examine whatever public pharmaceutical science you could provide."

"We can get you data on that!"

"Thank you!"

"Anything else?"

"I'm sure if I gave my assistants and the scientists a few days they could come up with a whole laundry list but I'm certainly not thinking of anything at the moment."

"Well, in a few days we'll be able to send another! We're having ships going back and forth every day."

"Is that a lot? I confess none of us have been able to grasp the full implications of this technology."

"It's a lot, but we want to be able to get any personnel who turn out to need to be here in place quickly. We're really invested in doing first contact right. We have subspace communications that let us talk to Amenta faster than the ships go, so a ship already on its way to Amenta can pick up things and people we didn't know to ask for before it left."

"That seems incredibly convenient--" they turn their head to look at some of the scientists they brought with, who look incredibly excited. "--and apparently technologically exciting, too."

"It is! It was relatively easy to figure out after we had the breakthrough that led to warp drive, but none of us are experts on how it works. Should we fetch some?"

"That would be incredible!"

"We'll let them know!"

A couple of days later a subspace communication expert arrives, and so does a sculpture for the merpeople to put wherever they think it would look nice (it's made of concrete with glass embedded in it to make it glitter in a lot of colors, and was originally intended to be sunken artwork, seized as a diplomatic gift at the last minute; it depicts an Amentan eel with some liberties taken on its color scheme).

The mermaids ooh and aah over the sculpture, which is then displayed at the edge of the shelf, so that it can be seen both above and below the water. Mermaid construction teams are busy creating a permanent diplomatic installation just off-shore with a permanent fiber optic data connection. In the meantime, the Amentans can access mermaid internet through the temporary ELF transmitter. 

The Amentans are all over mermaid internet! Their machine translation is getting better over time as they flag things for the computer to chew on harder and bring up persistent linguistic confusions with the merpeople. What's on the mermaid internet?

Lots of mermaid fiction! (Most mermaid science fiction assumes that other sapient life is also aquatic, but there are several that posit sapient flying aliens; terrestrial aliens ever show up but not often and mostly the authors don't seem to have thought through the implications of not being able to casually move in three dimensions.) Lots of mermaid Discourse! (About as much of it as on Amenta has to do with reproduction, but in different ways; other topics of dissent include people calling each other apologists for one side or the other of the Southshallowshelf War, discussion of ethical consumption habits, whether or not Akeekikekao did anything wrong, and sensitivity towards the disabled) Lots of mermaid science and engineering! (Their transportation is fairly abysmal) Lots of mermaid history! (Metallurgy universally started in the Deepdowns and worked its way up! The K'k'k'aouiiiia'keka Empire had a system of executing native citizens cleanly and sentencing people in conquered territories more harshly than necessary to compensate for the lack of native condemned criminals for cleanup and thus is generally considered to have been an unusually horrible polity even for an empire!)

Meanwhile, the Amentans have been thinking about how to let mermaids visit Amenta! Amenta does have an ocean but they don't know if it has all the things mermaids need to be comfortable. The suits don't look suitable for long term use, although a mermaid in a suit could maybe be in a wheelchair (a reclining one, if they don't bend that way) and toted around? For the day-and-a-half trip to Amenta maybe they could be in an aquarium tank? There are some large ones and they can be put on wheels, though they acknowledge it would not be the most stylish accommodation.

The mermaids have been working on the suits too--even if Amentans are going to come underwater mostly it still seems like a good idea. Mermaid tails are extremely flexible and the wheelchair idea should probably work, although it would be more comfortable if there were a pool or aquarium or something to retire to when not actively going around places. 

Okay! They can bring over a few big aquarium tanks of the kind you'd keep a large octopus in; it will be less roomy for the mermaid than the hypothetical octopus but it will fit through doors and stuff. And they can empty a big swimming pool and put mermaid-approved water in it for in between touristing.

Also, they have scuba gear and people who know how to use it now!

The mermaids will delightedly escort scuba amentans to the city, where chambers have been prepared drained of water and with amentan-appropriate furnishings! Some mermaids (who have been carefully vetted by the government, just in case) would love to visit Amenta!

The mermaids' tanks are rolled into the ocean to fill with presumably ideal local water and a mermaid apiece, and then they and their suits and any other luggage are rolled aboard a starship and brought to Amenta!

Scubamentans appreciate the air rooms (though they do want to make sure they're ventilated properly).

They're not ventilated directly to the surface but they do have machines doing gas exchange to make sure the air is an appropriate chemical mix that doesn't fill up on carbon dioxide and suffocate anyone.

Oh good! Then the Amentans will be quite comfortable in there between oxygen tanks, and go swimming around the mercity, taking tons of pictures with underwater cameras (plastic bags not being rated for this pressure).

This mermaid city is especially photogenic, having been built half-into a live coral reef. Mermaid architecture (at least as indicated by this particular city) is built into surfaces as much as on them. Plenty of things have walls for privacy, but within buildings or rooms things aren't really organized with a concept of "down" in mind. 

Curious mermaids are plenty attracted to the exotic, alien Amentans, although most watch from a polite distance. 

Most of the exceptions are small children too young to know any better. 

The Amentans love the little merbabies and will pet any merbabies who swim up to them and let them stick to the wetsuits if they can.

Merbabies can totally stick to the wetsuits. Merbabies are delighted to stick to the aliens and their wetsuits. 

Older mersmols have SO MANY QUESTIONS ABOUT SPACE.

The Amentans can answer space questions!!!!

Adult mermaids come collect their children from the Amentans when one or the other party leaves the place where they are, but are otherwise mostly content to keep an eye on their children and otherwise let them free-range. 

There are individuals and couples who don't obviously have any children, but nobody at all has exactly one. 

That seems reasonable to the Amentans.

They'd like to see museums! Are there those?

There definitely are those! This is a museum of art and this is a museum of science and this is a museum of history, which one do they want to do first? 

They'll split up!

Okay!

Mermaids don't really have paintings--that doesn't work very well as a medium underwater. But they have mosaics and carvings and statues and tapestries. 

The Amentans take pictures of it all and ask about the tropes represented.

This trope is Pre-Creche Mother Swims Away From The Babies She Didn't Choose, Crying and is a popular go-to if you want to make your audience cry. This trope is The Abomination and can be quality horror or cheap shock value depending on how it's used; these are all "quality horror" ones. This trope is seaweed in undulous shapes meant to evoke the form of mermaids having sex and is frequently used in borderline-erotic romance art. This trope is a heroic mermaid, either lethally wounded or fatally poisoned, swimming away from their loved ones to die alone because they're cut off from civilization and there aren't any corpse collectors. 

The Amentans are super into all this. What's the deal with the Abomination?

The Abomination was bad and evil and wrong. It was a fish. A predatory fish. That ate merbabies. It was bad bad bad. It's extinct now, thankfully. It was so bad though. 

Gosh! There used to be some things that ate Amentans but never as a primary food source. Most of them are extinct but they didn't actually do that on purpose except for a couple kinds, they just crowded most of them out with development. Some are still alive in the tropics or Arctic where few Amentans live and people have to watch out for them if they are there for some reason.

Well, Amentans were lucky enough never to have a period of development when they had to leave most of their babies to death by exposure or predation. That would change the ecological math a lot. 

Mermaids aren't in the habit of driving things extinct, and have in fact gone out of their way to avoid it when possible! It still happens, sometimes, but they've found it a sound policy overall. Why don't many Amentans live in the tropics?

Amentans don't season in the tropics, or the arctic! They get stuck in spring (the fertile season) and that gets really annoying after a while, especially if you don't have a credit.

Do they not have reliable birth control?

They have reliable birth control, but they want babies in spring more than the rest of the year.

Oh, huh. Mermaids want new babies less when they're naturally infertile but that's because they already have small children. 

Oh, yeah, Amentans who actually have a baby or even a one-year-old are usually fine with being in spring (though the sex drive boost can be separately tiring). It's just they don't want to live that way all the time even when they don't have a baby.

That makes complete sense. 

They are hoping to have fewer empty springs now that they can settle more planets! The merpeople's planet probably has too-short years, but they'd like to set up a camp for volunteers to see if any of them reseason.

Sure! The merpeople aren't using the land for anything, the Amentans are welcome to it. Although they probably want to talk to other merpeople countries before settling land adjacent to them. 

Yes, that makes sense! (Hey, merpeople internet of other countries, should they send more landing parties or talk to them online or what?)

(Talking online is acceptable but more landing parties would be preferred.)

They can send more landing parties! If there are merfolk countries not near any land that will be more difficult.

There are merfolk countries not near any land. One of them isn't close to any land but is pretty close to the surface and could build a floating platform to land on if the Amentans give them specs for what kind of landing terrain they need. 

The platform needs to hold a ship that weighs yea much and applies yea much force on landing.

They can do that!

Other merpeople countries are working out treaties with shore-bordering merpeople countries to send embassies to the shore. 

Tapa sends lots of emisarries in all requested directions. They want to be friends with all the merpeople.

All of the merpeople want to be friends with the aliens!

Some merpeople countries are similar, and some are very different. This one considers it impolite to discuss The Abominations in polite conversation. This one will only let you have biological children if you've raised a certain number of adoptive ones first, consent to reductive abortion, or have performed so many years of military or civil service, and removing the birth control implant of someone not approved for childbirth is a sterilizing offense. This one assigns each clutch a predicted eugenic value and requires that adoptive parents choose from the top five scored clutches currently at their local creche. 

These all seem reasonable, though it does mean the Amentans will have to get their information about Abominations elsewhere.

This one was experimenting with reducing clutch numbers by doing conceptions exclusively via IVF in one city but their data was confounded and a huge public uproar was caused when it transpired that one of the doctors working at the IVF clinic was secretly replacing sperm samples with his own. The doctor was executed but they had to discontinue the program because nobody trusted it. 

Oh no! What a sad story. Similar things have happened in Amenta; they have gamete donation charities aimed at mild springs and sometimes somebody unscrupulous messes with them.

That's terrible! It's always so awful when someone decides to be selfish and endanger the public good for their own benefit. 

They're agreed! It would be funny if they wound up running the charities for each other so no one biologically compatible would be handling the samples!

...Huh. That would be an idea. 

It would! It doesn't seem like an urgent first contact priority but maybe in a year or two.

Maybe! It could be tricky and they'd have to run some cost-benefit analyses but who knows. 

So the problem with reductive abortions is that they sometimes cause miscarriage, right? Have they tried things that seem obvious at a first pass, like coming up with some filler biomaterial to stick in there, artificial hormones to mimic the profile of someone more numerously pregnant, performing the abortion late enough that the remaining eggs will be viable even if ejected, using a slow poison injected into some of the eggs that will leave them alive for most of the pregnancy so they don't rot in there but not have them viable at the time they're laid...?

They haven't found a filler that both will expand at the correct rate to trick the body into thinking the "eggs" are still viable and won't be rejected by the immune system. Artificial hormones wouldn't work, the hormones don't change depending on the size of the pregnancy. The other two have been tried but the second doesn't reliably work and the first one causes health issues in the ensuing babies. Not huge ones, just regular prematurity issues, but enough that people wouldn't accept it at scale. 

Have they made any attempts at uterine replicators?

At what now?

Artificial wombs? Amentans don't have them but they have science fiction containing them and they aren't too farfetched.

They have incubators for prematurely-laid eggs but artificial wombs to start gestation from the beginning aren't something that's come up in mermaid science fiction much.

Maybe it would work and then they could just not miscarry small batches.

Maybe!!!

The suggestion is immediately submitted to some extremely official-looking medical forums. 

Awesome! The Amentans really really really want to solve the merpeople's problem, it's so tragic.

It's so tragic! It's so so much better than it used to be but that's...not saying much. 

That's really not saying much! They have some science fiction about r-selected sapients but it mostly assumes that for whatever reason those sapients are, like, okay with being r-selected.

r-selected?

Having a lot of babies so that most evolutionary selection happens in infancy. They're not classically r-selected - that conventionally refers to animals which (on Amenta) don't rear their young at all, let alone adopt others' - but it being impossible to personally invest in all of the offspring you have is the key thing there. On Amenta most mammals and birds can at least try to rear every baby that they have, although the state of nature still involves high mortality rates.

Oh. They don't have that as a bright line distinction, they just have a spectrum of involvement with the lives of offspring. Mermaids are pretty high on the spectrum, although they're topped by most birds, which don't tend to have more offspring than they can rear. Other points on the line include species which guard their eggs ferociously but lose interest once the eggs have hatched. 

It's not a completely bright line on Amenta either but it'd be less of one if they had more of the middle-ground species like the merpeople planet does.

It probably wouldn't really be possible to create a real civilization with "pure" r-selection, not that that stops the science fiction writers. 

Nothing stops science fiction writers!

Meanwhile, scubamentans are also investigating history and science museums.

The history museum clarifies that the Southshallowshelf war was the one in which someone accidentally dropped a corpse on someone else! Here is a gallery of artifacts relating to popular religious figures! These syringes were used for lethal injections by the K'k'k'aouiiiia'keka Empire! Here is a gallery of artifacts and explanations in rough chronological order concerning a mermaid civilization which went extinct about half a millenium ago!

Religious figures! What are mermaid religions like?

Mermaid religions focus around historical mermaids who are considered to be paragons of virtue, and their practice involves living according to that paragon's virtues. Theologian mermaids are ones who read texts by and/or about paragons and debate how such-and-such a paragon would respond to such-and-such an issue that wasn't around in the paragon's time and so forth. 

Not all mermaid religion focuses around generally-acknowledged paragons; some people hold up departed loved ones as personal paragons, or otherwise use less-popular dead mermaids whose virtues they consider relevant to their own lives. 

Interesting! Amenta doesn't have a widespread comparable tradition but some famous people are widely admired.

Their tour guide, who is an extreme history nerd who has devoured every historical text the Amentans have made available, comments that if Avalor had been a mermaid she would probably be a popular paragon for civil servants. 

"Avalor was the Voan governor, right? I don't know, towards the end some pretty bad things happened on her watch."

"I didn't really understand that part but anyway we really don't like empires these days."

"Yeah, nobody likes the Empire of Oahk."

Nod. 

More history! These historical empires over here weren't as bad as Oahk or K'k'k'aouiiiia'keka but they were still not great! They had thus-and-such non-reproductive negative effects on their conquered states!

What happened to that one extinct mermaid state?

Unexpected and really big volcanic eruption. There were survivors but they got folded into other nations. 

That makes sense. It's good to have the history preserved. These Amentans are not aware of any nations that have been completely wrecked by volcanoes, but now and then a city will have an issue.

Getting completely wrecked by a volcano is really rare. Most volcanic eruptions cause lots of problems but leave enough survivors that they can come back and rebuild once the water's safe again.

And what's going on in this here science museum?

This here science museum has a really fancy exhibit on robotics!

Gosh! Amenta's behind on robotics, because the red caste, recently phased out, was against automation, but they're trying to catch up now and would love to know what the mermaids know.

The mermaids have really really good computer science! The hard part of robots for them is keeping everything waterproofed that needs to be. This museum exhibit is mostly designed for laypeople and mostly contains "the very very basics of how robots work in theory" and "ways in which these robots are more advanced than their predecessors" but the Amentans can totally talk to mermaid roboticists if they want. 

They should set that up with Amentans who know more about the fledgeling field of Amentan robotics than these scuba divers do.

That makes sense. Meanwhile this robotics exhibit has neat interactive stuff. 

Fun!

Other exhibits include: ferromagnetic fluids, freight transport (which is better than personal transport, at least if you're not shipping breakables), mermaid biology, and Molecular Bonds.

Why is Molecular Bonds capitalized?

Because it's an Exciting!!! exhibit for mostly kids. 

Awww, cute. Hi merkids!

Aliens turn out to be more exciting than molecular bonds!

They wouldn't want to distract the merkids from learning! Suppose the aliens talk about molecular bonds?

WHOOOOOOAAAAAAH.

Parents from other parts of the museum start to herd their kids in the direction of the educational aliens. 

These particular aliens aren't molecular bond experts but they know enough to muddle through!