This dive site is a fantastic dive spot located in the Koh Lanta region. The dive site is actually about 20 km from Ko Lanta, in a southerly direction, on an island called Ko Muck Island. This is a great dive as it is quite unusual and offers divers the chance to explore the cavern and its many openings.

The cavern itself is about 30 meters long and is only partly underwater. This depends on the tide, which changes the depth of the cavern, but the maximum depth is around 12 meters. Visibility can be lowered by the tides and waves and so divers should try to visit when conditions are good.

The dive site is also known as Tham Morakot and when divers enter the water, they will see that the entrance is hidden. There is a limestone hole that is only visible below the surface at high tide. Once this has been spotted, divers should make their way past this and they will find the entrance to Emerald cave. They will find the cavern, which then follows a tunnel that leads to a lagoon. This is a lovely surprise awaiting all divers as the lagoon contains crystal clear water. Half way through the tunnel, divers can go through a small passageway that leads to a smaller cavern that has an air bubble. Divers can surface and explore the small cavern, and then continue on their dive. Alongside this spectacular journey, divers can spot most of the common reef fish of the area and some larger pelagic fish. This is a great dive and divers will have a remarkable experience here.