This mod changes the amount of time you can breath underwater.
It has 4 different files in it:
One for 5x the amount of time
One for 10x the amount of time
One for 25x the amount of time
One for 1000x the amount of time

Just pick one of the pak files, drag it into your PCBANKS folder and you're done!

PSA. I cannot get screenshots of it working in game because I cannot run the game on my system. I just mod for other people.