Just a feedback on diving.
Movements: you shouldn't be able to stop instantly, rotate without moving your hands/feet and so on. I think that a good way to explain it is the difference between a car and a boat, while driving a boat you have to plan the maneuver because it takes time to do it.
Also, you should be able to swim even when water isn't depth and eventually go prone to provide stealth untill your out of the water.
I know it's not very important, but it would make diving way more interesting imo.