Well they mention skimming or basially hovering around so I can see us floating over water for a bit till run out of "fuel" or whatever they will use to limit it and then slowly sink. Water capable machines can be in water but maybe not swim? Which we are supposed to have some kind of skin like shield around our operators and Mechs so I dont see why we couldnt have a certain ammount of time underwater due to this shield before you drain all your oxigen lol I am being realistic. But I cant seem why we cant sink and wait for thursters to be available again to come up and keep going, oceanfloor walking anyone?