To get shark skins you potentially have to come face to face with one of nature's most fearsome predators. Below are a few tips for making these encounters as painless as possible:
The safest way is to get a boat or jet ski and take it out into the water. Wait for sharks to come round the boat, then shoot them from your position. You can then go into the water to harvest the skins.
If you feel like being more hands-on, dive off the edge of the boat and let them come at you. They sometimes grab you which triggers as QTE (where you press buttons to complete actions) and these, if done successfully, will end with you being able to skin the shark.
Finally, try using your camera and scanning the ocean with it. You should be able to 'tag' sharks and then head out in a boat to find them - this will make it so you don't have to hang around out at sea waiting for them to come to you.
Added by: MongooseGeneral Dec 11th 2012, ID#5073