Tham Morakot is visited by swimming or by small inflatable boats. Starting from a ship, the swimmer has to enter the cave until he reaches a water filled chamber, which is lit by sunlight through a hole in the ceiling. The entrance passage is rather small and low, and it is passable only during low tide. If visitors miss the time inside, they have to wait for the next low tide to get out again.
The name of the cave means Emerald Cave. It describes the emerald colour produced by sunlight filtered through sea water. Inside the cave is a secluded beach of white sand.
This cave played a small role in the enormous desaster of the 2004 Christmas earthquake and tsunami of southeast Asia. When the wave hit the cave, two swimmers were washed in, battered, and killed. Eighty visitior who survived the wave were resued after five hours.
Another cave in the Hat Chao Mai Marine National Park is called Tham Chao Mai. It is located in the south of the park and is a dry cave above the sea with a small spring inside. It also only reached by boat, but it is not necessary to swim.