Sinkhole that clearly drains rainwater into an underground cave system, dry now but layered with water-marks. 

Weird maze of deep crevices. Very cramped, very easy to get lost in if one did not have a magnetic compass and inertial reference navigation software. 

...They go on the map. 

Water break. Pee break.

Power and oxygen check? 

She's been drawing about 45 W on average with the armor, and is down to 330 Wh remaining between her main and auxiliary battery (there's some kind of smart pick-where-to-draw-power switch that she doesn't understand the engineering behind, to minimize draining any of the batteries fully.) Naively, that means she can do 7 more hours and then she's out of juice. It might be longer if the heating needs drop as the temperature warms, though. 

She's breathed about 70L of O2, out of 400ish in the tank, and indeed her suit thinks she has about 325L left. The math predicts 27 hours remaining. The tank is still too full for it to make sense to transfer her current full canister and fill another. 

Okay. She in fact flat-out doesn't have the option of exploring all day; at some point she'll have to return to base, park herself beside the solar unit, and recharge the suit directly. Maybe she can take a nap at the same time, she doesn't really want to stay awake for 28 hours straight again. 

But, for now, she has power and air to spare for a trip down to the river to check if her crate of supplies is intact. 

She picked a good time for it. The ground is still frozen solid and everything on the surface of the rocks is pretty well dried out. 

An hour later: yes! it is! 

It's a little dented, but it's spare consumable medical stuff, none of it is, like, flammable or super fragile. 

The knots on the rope - and the knots on the seaweed - have been drawn tight enough that there's no possible way she's getting them untied. She'll have to cut them. She'll have a bunch of really short bits of paracord rather than one longer piece, which is less useful, but oh well, it's not like it's useless, and it's a worthwhile trade for the supplies.

...She'll probably kill this entire seaweed plant in the process, she entangled basically all of its fronds in her paracord. Well, she might as well harvest it and carry it up with her. Come to think of it, what actually happened to the one she harvested yesterday - she can't remember if she thought to secure it, she was so tired, so it could easily have blown away overnight. 

She should name the particular plant, there are going to be lots of "seaweeds" and naming something is a good way to start keeping a distinct mental bucket for it. Strapweed? That sounds stupid. Strapwrack? ...Okay, sure. 

Back up the stupid valley walls, wearing a whole lot of 3m and 4m strapwrack fronds draped over her suit and attached crate in various ways. 

That was a little more power-hungry and oxygen-hungry as an adventure. 2 hours 40 minutes, and she used almost 140 Wh on the suit and breathed 39L of oxygen. 

It's now been almost 9h since dawn. It still isn't that close to noon. The outdoor temperature is approaching 0° C.

Inside the tent is almost 20° C, and there are drips of humidity starting to ooze down the inside of her sill. 

Her solar panels are producing almost 40 W now. She’s banked 175 Wh. 

Redoing the calculations: she’s got 4 hours of suit power left, give or take. That’s the limit, not oxygen.

She kiiiind of suspects that once she stops moving she’s going to be stationary for a while. Might as well squeeze in one more exploratory hike before she takes an afternoon rest-and-literal-recharge break.

That shadow off in the distance might be promising…

It is! This sinkhole has a shallow slope into one side, filled in with packed gravel, and the other end is an actual overhang.

The cavity shelterer beneath the overhang isn’t huge, maybe four meters wide, two meters high, and one-and-a-half meters deep. …But it’s entirely below the grade of the plain, the sinkhole itself is at least four meters deep.

The giant slab of intact, uncollapsed stone forming the overhang had, at some point before the cave ceiling ahead of it collapsed, been eroded by a subterranean river into a natural arch shape. It’s cracked and bleached on the surface, like everything else, but it looks plenty stable.

The water-erosion was probably many millennia ago, and this part of the plateau has since been pushed upward by some geological force or other. It’s near the top of the local undulation, with no particular sign that it’s harbored more significant water flows that the rain falling directly into it in the last thousand years.

…The dark band at the base of the sheltered arch is not, on closer examination, actually a layer of different-colored stone. 

It’s a narrow crevice - no, a tunnel. The faintest air movement wafts near it. This sinkhole does still have a connection to the deeper network of limestone caves.

Merrin might be in love.

…With a cave. That’s kind of a silly way to describe it, isn’t it.

But this cave might well save her life every night from here on out, until such point as something else kills her.

She should really scope it out for hidden flaws before getting all attached, but…welp. She’s already attached. This cave will be her REPLACEMENT BOYFRIEND. It’s a deeply inferior replacement but at least it feels cozy and safe.

…Merrin is being very silly right now. But this is the first moment of genuine uncomplicated joy she’s felt since she DIED IN A PLANE CRASH. And, you know, who exactly is going to stop her from indulging in some emotional silliness? The Moon?

She trudges back to her camp, beaming to herself and already imagining exactly how she’ll set up her new out-of-the-wind, half-underground tent.

It’s been 10 hours and 35 minutes since dawn. 

The temperature is rising rapidly now. It’s already 10 C outside. 27 C in her tent.

Her solar panel output is up to 51 W. She has 252 Wh stored.

...It is pooossible that Merrin did not. Perfectly think ahead over her needs for the entire day. 

There are two ways to set up the multi-configuration tarp for her shelter: shiny side in, to stay warm, and shiny side out, to stay cool. For obvious reasons given her concerns last night, the shiny side is in right now. And there is not a super-easy standard protocol to flip it inside out without taking it apart, because on dath ilan you would not normally need to switch rapidly; either it's winter, and you're mainly worried about cold, or it's summer and you're worried about heat. 

She's storing up a ton of heat in her tent, and it'll be great twenty hours after sunset, but for right now she...is not going to be able to rest comfortably in there. Solar noon will be in three or four hours, the actual outside temperature will peak another couple of hours after that, yesterday it stayed pretty high for most of the afternoon and only started dropping more quickly after nightfall, and for that entire period her tent is going to be practically a furnace.

...You know what she should do, she should remove the big main storage battery right now. It's not great for holding charge for it to sit in temperatures above 30° C, she's supposed to Avoid That, and also she should probably only charge her suit part of the way and then just charge the main battery directly. It's sliiiightly better at holding charge than the smaller lighter batteries. 

When she's in the tent, she has the chance to notice that the bottom of her freshwater-collection pot is wet. There's not much standing water, yet, it's maybe 10 ml total, but the interior of the plastic is now continuously dripping condensation. 

...In a little while Merrin is going to dig a pit to set up a second still out here. It's working but she's getting quite low on drinking water and she has a very long night ahead of her. A long time ahead of her, admittedly, nightfall is still at least 17 hours away if she counted yesterday right, but she still doesn't want to make her bet on getting a liter to drink this afternoon and another two liters for the night. She's definitely not optimally hydrated, right now, which is admittedly convenient when peeing is a whole complicated thing. (She's avoiding just peeing in the suit absorption pad, since she does have slack to do the really annoying thing instead and she is, at some point, going to have to painstakingly clean and dry the stupid pads for reuse.) Anyway, it might be convenient but it's not, like, great for her organs long-term, and is generally best avoided. 

…For now she’s going to take a break from the suit, actually, to eat and pee and just…not be wearing power armor…it’s not that it’s uncomfortable, it’s very well fitted, but she does start to get tired of it after a while. And it’ll charge a bit faster if it’s not running while it charges, and she can sit with a pulse ox probe on her finger and see how long she can go before she feels unusually stupid. 

The air temperature is lovely, actually, however brief that’s going to last.

…Now seems like a good time to retrieve her multipurpose foldout screen for viewing digital materials, download all of her suit data to her main computer storage and wipe the suit memory (it’s not unlimited and will start erasing earlier recordings to make space after about 150 hours of use, which at this rate won’t take much longer to reach), and then, while the armor charges from the solar panels, she’ll pull up her route data as a map and recopy her hand-sketched approximate map with the correct distances and angles.

This is strictly speaking more effort than she needed to put into hand-drawing her map, it did not need to be an art project that somehow took her over an hour and it's possible she's just a little spacey with her pulse ox reading persistently at 89% and fugued on it. But, consider: it's preeeeeetty. 

[AUTHOR'S NOTE: length of distance arrows on the grid scale is REALLY borked, the written numbers are the correct ones.] 

....Suit back ON, for the O2, and she'll give herself 21% for fifteen minutes before turning it back down in case it unstupidifies her. 

(It doesn't actually seem to do much, so maybe it wasn't that. There are honestly a huge number of reasons why she might be in a weird headspace right now, from "this is a lot of social isolation for her, actually" – it's very rare that she does a sim with no radio backup that lasts more than a single dath ilan day – to "she's really stressed about the exoplanet trying to kill her and is missing all of her usual stress-relief humans", to "she DIED in a PLANE CRASH and that's probably traumatic or something.") 

Where are her numbers at. She has so many numbers to track but at least they're finally maybe sort of starting to become intuitive like vital signs. 

12 hours (and 5 minutes) since dawn. Rechecking the angle of the sun and doing a coordinate sketch of her measurements so far, it does look like solar noon will plausibly be in about two hours, which checks out for a 28-hour day. 

It's now 16.6° C outside, with a soft gentle breeze wafting up from the ocean. 

The temperature during her suit break was perfect, though she is realizing, belatedly, that she should really have been more careful to keep her hands out of even indirect sunlight. She was wedging herself into the shrinking patch of shade side of her tent, and she was still wearing the undergarment that goes with the suit which is pretty full-coverage and she grabbed a head and eye covering, but somehow hand sunburn did not occur to her and she did not have the backs of her hands covered the entire time. 

Well, the damage is limited now, and she'll have to remember that the UV here is not comparable to a "high UV" day in dath ilan.