Along the islet of Hin Phae, especially, the best chances of seeing these creatures is by snorkeling. Blacktip reef sharks are known to shy away from the noise of the bubbles that diving tanks make, and tend to shelter themselves from divers. Hin Phae is a popular snorkeling site, located 200m west of Long Beach, Ko Phi Phi Don. It may or may not be a stop on your boat tour, but you can schedule a visit separately as well, right from Phi Phi Don.