When you arrive, you will see a man giving out shark fins. Theese here are optional to have. If you keep going, you will see a man selling coconut milk. You'd better get this now, since you will need it soon. Now keep going right until you see a man selling grass skirts. Theese are needed, too, so I would put it on right now if I were you. But I'm not. :3 On the way to the grass skirts, tou probably saw a weird cave looking thing. You will go inside after grabbing the paper floating around above it. You will get it by pushing that block over to the vine hanging by the tree, Go to the second boardwalk thingy and jump, trying to land on the building.
Now enter the building/cave dealy, and go to the top left. You will see a face type thing, and you shall click on it. Click the one that means O, then the one that means P, then the one that means E, then the one that means N. O - P - E - N, in that order. The eyes will light up green, and a door will open. Go! Then go right, off of the vine, until you find a bat boy. Talk to him if you like, but you don't need to. Keep going until you find a gap that has spikey walls. Go down and grab the dinosaur bone.
Get back up there and don't fall this time. If you do fall, just keep trying. Then go left. Keep going until you see a pot. Grab it and climb the vine next to it.
Go back to where you first entered the cave. Push the block back to the tree vine, and get to the complete top of the tree. Now you will see why you needed a grass skirt. Wear it before you talk to the Medicene Man, or he will say
But if you put it on and give him the stuff, he will make you a coconut calming potion for you to feed the shark.
Now, go back to the bay where you first got the grass skirt, and keep going until you see a cannon. Click the sign that says "Feed The Shark!", and you can shoot your new coconut out of the cannon.
Go back, then swim past the sleeping shark to the other island. You will see a man and a boy. Click on either, then lead them back to the main land. The lady will thank you for saving her son, and the old man will give you the medallion.