I think it would be a great idea to be able to utilize air bubbles, that gather on plants, branches and leaves under water, to replenish the oxygen meter while swimming.
I think that another great idea would be the addition of aquatic creatures such as frogs or fish. It will add an extra danger element, even more harvestable resources and, thus, even more craftable equipment.
I really am enjoying playing Grounded and I am really looking forward to seeing what the future has in store for this game. Thanks a ton, Obsidian.