Established in 1981, 400-sq-km Ao Phang-Nga National Park is famous for its classic karst scenery. Huge vertical cliffs dominate its 42 islands, some with caves that lead into hidden hôrng (lagoons surrounded by solid rock walls). The bay is composed of large and small tidal channels (Khlong Ko Phanyi, Khlong Phang-Nga, Khlong Bang Toi, Khlong Bo Saen), which run north to south through vast mangroves and function as aquatic highways. These are Thailand's largest remaining primary mangrove forests. Ao Phang-Nga's marine limestone environment conceals lots of reptiles, such as Bengal monitor lizards, two-banded monitors (which look like crocodiles when swimming), flying lizards, banded sea snakes, shore pit vipers and Malayan pit vipers. Mammals amid the mangroves and on islands include serows, crab-eating macaques, white-handed gibbons and dusky langurs. In high season the bay becomes a clogged package-tourist superhighway. But if you explore in the early morning (best done from Ko Yao Noi or Ko Yao Yai) or stay out a bit later, you might just find a slice of beach, sea or limestone karst of your own. The most fun way to experience the park is by kayak. At the time of research, there were plans to introduce compulsory advanced e-ticketing for the national park.