In the Shark Tooth Island, you need to find these things: a carbonated coconut milk, a part of the hammerhead's journal, an old bone, a grass skirt, the key ingredient, the old medicine man, Prof. Hammerhead and a boy. Your mission is to calm Booga and save the old man and the boy.
The first man you will meet here is the one who sells you a shark fin. If you want a shark fin, click him and he will give you one. Then outside the Coconut Cafe, click the man and he will give you a carbonated coconut milk (this is important in your mission). Then go to the Ancient Ruins (watch out for the falling coconuts!). To get the Hammerhead Journal, push the block to the tree. Use it to climb the tree to the top (do not go up the arrow symbol) then jump left and get the journal. Go inside the building. Find and talk to the man in yellow and he will tell you how to use the code from the journal (Here's how: Refer to the code: Click the symbols that will spell "open" and press the "nose"). Go down (avoid the giant caterpillar!) and go the left. There you will find an old bone in the mouth of an animal skull. Then go up, the to the left then down (hint: the key ingredient is near the hieroglyphics on the wall). Pay attention to the writings on the wall for it will instruct you how to use the coco milk, bone and the key ingredient. Find your way out by climbing on the vine on the left. Go to the Booga Bay to get a grass skirt. As much as possible, talk to the woman beside the grass skirt seller (she's the mother of the boy). Go back to the Ancient Ruins and climb to the top tree (again, watch out for those coconuts). Wear your grass skirt and talk to the old medicine man. Give him the Carbonated coconut milk, the old bone and the key ingredient and he will give you a calming potion in a coconut. Go to the Booga Bay and swim to the next island with the signboard "Feed the Shark". Click it and feed the calming potion to Booga to calm him down. Swim to the next island and save Prof. Hammerhead and the boy. Go back to Booga Bay. Prof. Hammerhead will give you your medallion.