Beginning an underwater game

I have been searching for a while, but couldn’t find any documentation of it. I want to make an underwater first person shooter. I was thinking about the character controller, and was wondering if you could edit the FPS controller script to allow for the character to move where ever it’s facing, so if it’s facing up, it’ll move up. Also, maybe something like space makes the character go up, instead of jump.

Yes, you can edit the Character Controller script and make it do whatever you want.