Koh Tao means Turtle Island, if you are expecting seeing turtles, you are right! The island is important breeding ground for hawksbill and green turtles. Other famous sea creatures to see are Black Tip Reef Sharks (can be spotted on many beaches), lucky ones might meet whale sharks too!
You do not need to be a certified diver/freediver to enjoy the underwater beauty around Koh Tao, you only need a snorkel mask to explore the undersea life. Snorkeling is easy and convenient – many sandy beaches offer easy access to the water, shallow, wind-protected bays make snorkeling safe. Please be aware that many beaches don't allow fins any more due to coral protection. Andn for Ko Nangyuan, a small island very close to Ko Tao. It is famous for its diving spots and its great snorkeling beach you will find many tropical marine life and beautiful coral reefs in these breathtaking islands!