Tham Phet, i.e. ‘Diamond Cave’, is the name of a cave in Krabi, located on the small peninsula of Railay. This small limestone cave is about 130 meters deep and has a bridge-like walkway for visitors to facilitate sightseeing.

It is home to some Micro-bats (fig.) that dwell between its stalactites and stalagmites. The cave is also known as Tham Phra Nang Nai, i.e. ‘Inner Princess Cave’ or ‘Inner Queen Cave’.