Shark! Hunting the Great White Tips
When you first start, go to the bottom and go left. When you reach the mountainside, follow it to your right all while staying at the bottom. If you do not do this, it will be easy for the sharks to attack you. Eventually you will see a crevice in the mountain to your left. Go in it and look down. You will see a gold necklace. Swim to it, then get back out and kill the two yellow sharks to get the Improved Suit.