Emerald Cave is a cave located on the west coast of Ko Muk Island,- The paradise island of Ko Muk and Emerald Cave are part of the Trang Provence, Southern Thailand. The cave has a narrow 80 m long tunnel. The cave can be entered either by swimming or by using a kayak. It is best to see the cave at mid tide, because at low tide there will be no water, hence no 'emerald' on the beach inside. Outside the cave, there is a lagoon which is surrounded by tropical plants and a beach.