If you drown for swiming to long they made it more realistic then san andreas style of swimming. No one can swim for ever and never get tried. maybe thats what the swimming side missions are for. Build up so you can swim longer and faster
the game comes out oct 31 in canada. Edsion Carter said that he was going to make one final version but did'nt. I don't know if anyone knows but on gtaforums waterbottle made his own custom mission