Hint: Avoid Jaws:
When Jaws has attacked your boat and you are swimming in the water fighting him, go to the very top of the water. Jaws will not touch or harm you. This, however, will not save you from the stingrays, jellyfish, or other smaller sharks.

When you are fighting Jaws in the water, you can hide on the top of the water where he cannot get you. However if you go just a little lower you can still attack him and he cannot get you.

Hint: Submarine:
If you find the submarine, which is usually in a cove on the bottom of the level or in the middle of the level, your speed will increase. If you get hit while in the submarine, you will turn into a person again.