You will have to collect all the prizes found under the water, which is mentioned as you proceed to each stage.
Complete collecting the prizes within the time duration as otherwise you will have to try again.
There are three stages in the game, and as the stage increases the depth of water level increases.
You will have to help the character collect the prizes.
You should also help the character in avoiding enemies found under the water, as otherwise, your life strength decreases. Avoid contact with the fishes too!
If the character is in need of energy, there are gas tanks that can be utilized to gain energy.
Use left, Right, Up and Down arrow keys for navigation, and as the character gets near a prize, use space bar to collect the prize.