A small isle 800 metres south of Koh Tao, Shark Island boasts excellent snorkeling, particularly around the northwest, where shallow water can be found.
The island is named not for its carnivorous marine life but for its resemblance to a shark fin from certain angles. The occasional currents bring in nutrient-rich waters, encouraging abundant marine life. Groupers, turtles and schools of raccoon butterflyfish inhabit the shallower depths, and nudibranch nurseries line the eastern coast. Take a boat to get here, or rent a kayak from Aow Leuk or Sai Daeng Beach. It only takes about 15 minutes, but be aware of strong currents in the channel between the two islands.