Okay. 

Merrin needs Case 1 because the atmosphere isn't breathable, that's non-negotiable. She needs power, or she dies after the battery power runs out for the oxygen concentrator; Case 4 is also non-negotiable. 

She needs shelter. She does not have the option of building one with local materials. 

She needs food. Ideally all of it, to buy more time to figure out which local lifeforms are edible with what processing. 

Honestly, the only boxes she doesn't really desperately need are Case 5 and Case 7, all the backup medical supplies. Except that, one, she might well end up injuring herself, and two, her trope-sense is tingling and insisting that it would be TOTALLY ON THEME for this stupid survival scenario to somehow also involve someone showing up with a medical emergency. Merrin does not THINK that's how any of this works, because it would be so incredibly silly, but given her spectacular levels of uncertainty around everything she thought she knew about Reality, she's not SUFFICIENTLY CONFIDENT in that to entirely discount it. 

Since transport would also be a significant issue in the survival scenario she had been expecting to need this gear for, the boxes lock together, and in theory she can lock together four of them and lock that onto a harness and the power armor would let her carry that many at once. 

In theory. In normal gravity, on reasonable terrain. Merrin is absolutely not going to risk it at 1.2G when needing to scramble up uneven, potentially slippery slopes. Too much risk that she would at some point slip and fall and tumble end-over-end all the way to the bottom of the valley again, which could injure her and might damage the power armor and would definitely set back the timeline. 

Two at a time, then, and she'll just have to keep an eye on the receding tide and do as much as she can. 

Even laden, it's a little faster; she has her route planned, and the terrain is steadily drying out; the mucilaginous rock films retain water remarkably well, but the surfaces eventually dry out to a waxy texture. They're surprisingly tough, too. Even with all the extra mass she's carrying, the treads of her boots don't shred them. 

Well, they have to go through a lot, what with the violent tides blasting up and down this riverbed on a twice-daily basis. 

It's now slightly less than five hours after dawn.

The sun is...higher. It doesn't look anywhere near the zenith of its arc through the sky. It's noticeably an angled arc – which makes sense, for winter at a temperate latitude – and it's a little hard to judge when Merrin keeps changing position and viewing it from different angles, but eyeballing it, the sun is maybe a third of the way up the arc its tracing. 

Eyeballing it isn't good enough for planning purposes. Merrin is going to pause for five minutes, despite the time pressure, and kludge together a sundial out of fragmented bits of shale and, when it doesn't want to hold together as sturdily as she prefers, a mouthful of water from the built-in drinking bladder in her power suit, mixed into one of the exposed patches of hard-baked dry clay to make it into, instead, sticky wet clay. 

She marks the sun's current shadow with an indelible marker - she has one of those in the small light front-pack clipped to her suit where it's not in the way. 

And then back down. ...Temperature check? 

It's now -17º C. 

That's a twenty-degree increase in five-ish hours.

If she's eyeballing it right, solar noon might not be for another ten hours, and the temperature will probably peak a little after that. 

...Merrin now has a hypothesis for why there aren't any icebergs. 

Again, it takes about an hour to scramble all the way back down and return to her remaining boxes. 

(The tide, so far as she could tell, was even further out when she was climbing down and had a good view. From her current angle she can no longer see ocean at all, just the river itself, still working on icing over but in another five hours that's going to start reversing course.)

Almost three hours per trip, once you take into account loading and unloading. She won't have to climb down on the last one, but that's still eight hours to get everything else and that's assuming she doesn't rest at all. 

She has longer than she feared. This ridiculous planet clearly has a longer day-night cycle than what she's used to, and the tidal cycle should be (approximately) (at least, assuming there's just one moon) tied to the length of the day. With high tides specifically twice a day, she thinks - yeah, she's remembering that right, the "tidal bulges" are on the side of the planet facing the moon and, symmetrically, on the opposite side, and rotate as the planet rotates under the moon. 

...She hasn't seen the moon, so the last high tide must have been the tidal bulge opposite the moon; otherwise, low tide would correspond to moonset, implying the moon had previously been visible the entire time. (She thinks "low tide is always moonset" holds? She doesn't know how long a full orbit of the moon would take - it depends how fast the moon is moving relative to the planet, on dath ilan the "lunar day" determining tides is almost an hour longer than the solar day as the planet "catches up" with a moving moon - oh, no, and she's also doing some approximation, she thinks moonrise-to-moonset isn't always exactly half of the lunar day period, it varies based on...stuff...that she knew some facts about once that she cannot retrieve right now and probably can't figure out on the fly for another planet anyway so it's irrelevant and she'll need to determine it empirically...) 

- approximation is better than nothing. Low tide is moonset or moonrise. She hasn't seen a moon yet, ergo, it's not yet low tide, the tide is still going out. Once she sees the moon, she'll know its on its way back in. 

...The tide seems to have been draining out at a rate of somewhere between one and four meters per hour depending how far she trusts her eyeballing. In theory, knowing that the "lunar day" is closeish to the solar day should, once she has a sundial measurement to sanity check her sun-eyeballing, let Merrin estimate the duration between high tides and, given the per-hour rate of water dropping, get an estimate of the total tidal range that way. Ish.

Merrin is really hoping it's closer to 1-2m, because 4m and a day that might be 30 hours long - a winter day! in addition to her first uninformed wild guess that it surely can't be -40ºC in summer or she would be in a glacier right now, the sun's trajectory is compatible with winter-at-temperate-latitudes, though she has no way to estimate her actual latitude without knowing the planet's axial tilt - anyway, if a winter day is 30 hours, then who knows maybe the night is 50 hours and an 80-hour solar day divided by four is twenty and twenty times four meters an hour would mean EIGHTY METER TIDES and that's pessimistic wildly-approximate-math, it's probably more like her 95%-confidence-interval for maximum tidal range than her 50%-confidence-interval, but it sure is a terrifying 95%-confidence-interval upper bound to be assigning. 

For now: there's still no moon in the sky. Not low tide yet. She should focus on hauling boxes. 

Two hours later - seven hours after dawn - and she's dropping off more boxes at the top of the slope and making a mark on her sundial. It's not an accurate enough sundial to be certain yet but it does, in fact, look compatible with "sunrise to sunset will take about 30 hours". 

...Check on ambient temperature trends? 

-9 º C. 

The ocean is....just, barely, visible, as a strip of glimmering purple-maroon that might be a whole ten kilometers away. 

STILL NO MOON. Not that Merrin wants a moon, because she doesn't want it to be low tide yet, but it's still mildly driving her nuts not knowing.

She mostly hasn't been itching too much about the lack of prediction markets - she's done a whole run of training sims recently with only low-bandwidth voice-on-radio backup, specifically to practice decisionmaking under stress without all the smartest people in the world feeding her advice via prediction markets, and she managed to successfully discount it as not worth being mad about - but right now Merrin would REALLY LOVE if the twelve most excited astrophysicists in dath ilan were eagerly debating every single data point available and narrowing down probabilities. She's pretty sure she could be doing more with observations she could make if she knew to make them, and it's just that she's not a superheated expert in tides, or in any of the several thousand fields of expertise that are not specifically emergency medicine but would be A LOT MORE HELPFUL right now. 

...At least Merrin is unusually well-prepared for one element here, which is repeatedly hauling very heavy storage crates of life-critical emergency supplies up a giant limestone slope, while under the effects of 1.2G, and also keeping the suit power-assist as low as she can cope with to save on battery life, and resisting the temptation to bump her air up to 25% oxygen for the stamina boost because she doesn't know how many problems she'll have with solar generation, and doing all of that for what's going to end up being nearly twelve hours straight. 

It really feels like the universe is trolling her.

Cases 1, 2, 3, and 4 are now at the top of the slope!!!! Merrin has oxygen, power for the oxygen, the makings of a shelter, and 15 days of food! 

Merrin scrambles down as fast as she can. She's definitely going to have time to grab Extended Provisions and Extended Medical. Whether she has time for the box her armor came in - light, since she's wearing the others, but unwieldy enough that she doesn't want to attempt to paracord-tie it on top of two other crates - or for the Redundant Medical Supplies, depends on when she sees a moon and how scary the incoming tide looks. 

Tidal bores are unpredictable, is the thing. You don't get a steady flow, you get a small incoming tide – because most of it is getting hung up in the narrowing river-mouth inlet - and then you get a wave bringing tens of meters of tide all at once. She thiiiinks she read one time that you can get tidal bore waves nearly as high as the total tidal range in a region, though that takes very specific conditions and geography and she's probably not that unlucky. Unless the universe is trolling her. 

Anyway: there's a discontinuity, turning a smooth water-level graph into a step-function, and there might be physics to determine when the step happens but Merrin doesn't know it and it would rely on measurements she has no way to take. She suspects it means that the point where her stuff is will be flooded sooner than it would otherwise, because it's at least ten meters below high tide and at least ten above low tide and so, approximation, it's exactly in the middle, and probably the step-function jumps from "tide is below what the naive math predicts" to "tide is above that" across the middle of the tide graph?

...Or possibly Merrin is incredibly confused because she's trying to visualize hypothetical graphs of water levels in her head while hauling stuff up a hill. 

She's halfway up the limestone slope - moving a bit more slowly, now, she's starting to risk fatigue - when she sees the moon. 

It is a superheated enormous moon. ...Well, strictly speaking Merrin has no way of knowing if it's larger than dath ilan's moon or just closer, just that the angular diameter as seen from the planet's surface is a lot larger. (There's probably some sort of astrophysics where one is related to the other but she doesn't know it and cannot rederive it from basic principles on the spot in her head while hauling crates up a hill.) 

That...would in fact explain the enormous tides, wouldn't it. 

Top of the hill. An hour later, according to her suit clock, and it's now been ten hours in total since dawn. 

The temperature is now 0.2° C. Positive 0.2° C. The ice is about to start melting. 

The sundial, and also Merrin's eyeballs, think the sun is about two-thirds of the way to its zenith. More likely to be a bit more than that than a bit less, but...call it a 30-hour day.

Merrin should try to estimate how close in angular degrees the zenith is to "directly overhead", once the sun is there, that'll let her do some math and figure out roughly how much longer the night is than the day? ...Is that true, or would it need to be stupid guesswork math because she can't untangle "different axial tilt" from "exact latitude" or "exact season relative to winter solstice and nearest equinox"? - no, she thinks if she can get a sense of where the sun rises and where the sun sets and estimate that as a fraction of the total...horizon circumference? there's got to be a better term than that? - but if she knows how "small a bite" of the sun's arc happened above the horizon, relative to if it were passing directly overhead at a 90 degree angle and the day and night were exactly equal, she can figure out how much of the circle is left "under" the horizon and thus the relative durations of day and night?

This is definitely math she needs writing materials for, it's been a while since she had any reason to do math like this. Fortunately, her gear includes a reasonable quantity of (tough, waterproof) paper, plus writing utensils for it. She'll run out food before she runs out of notebook space. 

...And low tide was an hour ago. 

She can almost certainly make it down and back. The ocean still looks very far away and she still can't see or hear the roar of a wave surging up the inlet. It seems likely that the interval between low tide and high tide is, like, fifteen hours or something, and ten hours ago her nearby spot was already above water, so it's probably more than halfway up in terms of elevation. She doesn't have another ten hours, because of the tidal bore effect, but it would be really quite baffling if she had less than two hours. The tide looks like it's gone out past the eroded cliffs at the mouth of the river inlet, so initially it's going to be rising normally without encountering obstacles to concentrate the forces. 

It's worth a tiny risk, for the benefit of backup medical supplies that could mitigate other risks later. And it would be really nice to have a way to store her armor securely where it can't get damaged by the elements.

Merrin isn't certain, though, and so it's going to be an intensely nervewracking last trip. 

The trip down is rapidly becoming noticeably more difficult than the previous three trips were.  

The thing is that the ground was previously frozen, and froze within seconds to minutes of being exposed by the tide. Which created its own hazards, of course, but the black-ice tidepools were visible and possible to avoid, and much of the rest ended up freezing with a sandpaper texture that did not create additional slipping hazards. 

Now the little pockets of trapped water are melting. They'll almost certainly dry out the rest of the way under the bright, increasingly hot sun, but in the meantime, it takes Merrin 50% longer to safely make it down. 

By the time she's back at her stuff, the air temperature is still only up to 4° C, but the surface level of the frozen tidal silt is absorbing the sunlight and melting. It's quickly becoming very squishy. 

Merrin - somewhat unusually for her social group - has spent enough time near oceans to have an intuitive-level prediction about how long it would take for the silt-mud to bake in the sun and dry out a bit and have less of a tendency to try to eat her boots. 

...Longer than she expects she has. 

Well, nothing for it but to load up again and trek back. 

Merrin plus power armor weighs around 130kg. (It's not the kind of armor that would deflect high-energy projectiles; it's designed to make her able to carry more with less fatigue and to safely operate underwater and survive being banged around a bit, but it's also optimized to be lightweight and have as long a battery life as possible, for scenarios where she's a long, long way from Civilization and a reliable power supply. The armor itself still weighs more than she does, but only slightly more.) 

Another 35kg of boxes is "just" a 27% increase in mass. But it's mass in a location that shifts her center of gravity, and the thawing ground is trying even harder to eat her feet.

...Merrin might, perhaps, have prioritized suboptimally here, though admittedly there's also an element of poor luck. 

She could have done this ten hours ago, no problem. She would be having a somewhat easier time now if she had EATEN MORE CALORIES, which she hasn't, because she would have to unseal the suit helmet to eat a meal bar and she didn't prioritize taking half an hour to set up the oxygen concentrator, partly because she was worried about leaving it exposed to the frigid cold and draining its battery life, but she could have caught onto the trend like SIX HOURS AGO if she had been PAYING ATTENTION and guessed that there would be a window of totally innocuous temperatures. 

Anyway. She's had maybe 800 calories worth of meal replacement liquid, by dint of just pouring it directly into the drinking bladder built into her suit, which she can do without removing the suit though she's perhaps going to regret it when she has to clean it later, normally she sticks to electrolyte powder in there.

(She can, fortunately, pee in the suit, and it doesn't even involve having to catheterize herself, there's a pad of super-absorbent material that wicks the moisture away. She'll have to dry it out later and reuse it, she only has one spare.) 

She does have a couple of meal bars in her front pouch but the problem remains that she would have to unseal the helmet, and either breathe low-oxygen air or, like, override the "open helmet" alarm and waste a lot of the air supply blasting oxygen out the front of her open helmet. And stopping to eat won't actually fix the whole problem. Her body doesn't just need a meal in her stomach; her muscles need rest. 

And she can't afford to stop here, because it's POSSIBLE that she has only ONE OR TWO HOURS until an enormous wavefront that could be up to 25 meters high and will be moving at 50 km/h bears down on her. 

(She probably has longer than that, and it might not be quite that high; tidal range varies. But if Merrin makes a habit of taking risks because it's 95% likely to be fine this one time, then all those 5% risks of disaster will RAPIDLY COMPOUND. She has no backup, here.) 

...Can she manage without the boxes, or has she just thoroughly misjudged her endurance and doomed herself here?