Underwater, look for the candle kelp plants (they are always a little different) but generally remind me of a candelabrum upside down. Use E when near and they will replenish your oxy.

Hiding underwater is not a super good idea unless you have some S class underwater upgrades. They can be replenished with oxy.

Best course with most sentinels is just outrun them. They will give up and quit being mad. On extreme sentinel worlds, they never really give up and will attack you on sight-regardless of what you are doing. Best on those worlds is to keep running, jump up on buildings to scan or find their Nest thing and disable it. That will eliminate all sentinels on the planet until you leave.

If you jump in your ship the sentinel ships will start attacking if you have a wanted level. Best to avoid that unless you plan to make a run to the station or call in the anomaly.

Ok that sounds helpful (though it does not answer the question about how running out of oxygen makes sense when my suit is loaded with oxygen).

Also, though, I was doing the tutorial, and landing on the second planet the sentinels had popped up next to my tutorial goal. So I am not sure how running away would have helped. (So... I guess I would want to start a third instance of the game to avoid them entirely. But I am trying to figure out if I want to try, or whether the game's sensibilities are too janky for me to have fun with it.)

Oxygen charges your life-support which only provides the equivalent of what would be stamina in other games.

In order to breath underwater for any length of time you need an underwater protection module (purchased from space-station vendors)...which can also be charged with oxygen, but is a totally separate unit,

Not exactly intuitive, I know, but that's how it works :)

And as for sentinels - there are 3 levels, but only on planets where they are described as aggressive (or something similar) will they attack you on sight. Other planets where they are ever-present (or similar) they will only attack if you persist in mining etc. after getting a warning to stop. And finally on planets where they are sparse or absent, you'll hardly see them and they'll only attack if you attack them first.

So sentinel fights are easily avoided, and it's probably best not to tangle with them until you have the equipment and experience to deal with them.

There IS an upgrade that lets you syphon the air back out of your jetpack and sprint assist systems, but remember, breathing jet fuel is harmful to your health.

Long story short, the O2 you put into the life support, it's mostly used to make rocket fuel for your jetpack, not breathing.

Originally posted by ICountFrom0:

There IS an upgrade that lets you syphon the air back out of your jetpack and sprint assist systems, but remember, breathing jet fuel is harmful to your health.

Long story short, the O2 you put into the life support, it's mostly used to make rocket fuel for your jetpack, not breathing.

But by default we're wearing a space suit? And life support works fine in low atmosphere locations?

(The story might make sense if water was shorting out or gunking up our equipment. But "not being able to breath" underwater, where we're geared for breathing indefinitely in much harsher conditions feels wrong.)

Space suit? Have you TRIED leaving your friggate and actually being in space? This thing has NO protection against vaccume at all.

And yes, airless moons draw out of lifesupport REALLY fast, almost as if it wasn't actually meant to keep you breathing.

I have done none of this yet - I had just started the game a couple days ago.

Still, if we can use life support to breath on airless moons (granted, with frequent additions of oxygen), I do not understand why we cannot use the same mechanic underwater.

Originally posted by Wisp Cat:

Still, if we can use life support to breath on airless moons (granted, with frequent additions of oxygen), I do not understand why we cannot use the same mechanic underwater.

It's an optional extra; see below for further details.

Originally posted by ICountFrom0:

There IS an upgrade that lets you syphon the air back out of your jetpack and sprint assist systems, but remember, breathing jet fuel is harmful to your health.

OXYGEN REROUTER
Emergency Life Support System

Upgrades the Aeration Membrane of the Exosuit to harvest oxygen from the Life Support system in the event of a breathing emergency, allowing the user to resurface and seek conventional fuel supplies.

Note: Long-term conversion of life support energy to breathable gas is not recommended, and may result in life no longer being supported.

Blueprint available from Iteration Selene at the Space Anomaly; strongly suggest you supplement your Life Support system with ancillary modules procured from space station vendors, vanquished sentinels and autophage camps for maximum utility.

Also, Efficient Water Jets.