If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Hunt in 24 spots all over the world and try to catch as many fishes as you can. Each time you earn enough money you can unlock another hunting area, and spend the money on better gear (like weapons, oxygen etc) Watch out for the bigger fishes and sharks that might attack you!
W, A, S, D - Swim around in the water.
Mouse - Aim / Shoot.