Leave No Trace achievement in Under the Waves

How do this is covered in the prologue. You can find some oxygen sticks on the wall near where you enter the submarine (moon) for the first time - if you use one with you'll drop the plastic case on the ground. Pick it up with . Just use and pick up the remains of 10 for the achievement.

You can find more oxygen sticks around the world, at Docking stations (a cog symbol on the map), and on day 2 you'll be able to craft them (I believe you are given the blueprint in one of the crates outside your base rather than having to find it).