Making water to swim and dive in

LavaWave

Is it possible somehow? For FPS mode where you can swim up and down and gave an oxygen meter? It gets replenished when you resurface of course.

Let's say I want a pool where you go in and dive to enter an underwater tunnel to progress, is this possible? Will it be possible in a future update?

YtheL2

I'm not sure about swimming, but an oxygen meter should be easy to make when the player is below a certain height. You can also just make tile triggers for the oxygen meter to appear.

Person

You could also decrease gravity when below that height.