For centuries Thai monks have used remote caves for meditation. With most of Thailand's forests gone now, many of those caves are accessible to the public. A few are major tourist attractions. In some cases, a temple has been built above the cave. If a cave has been used by monks, it will probably contain statues of the Buddha, hermits (lersi/reusee), or other sacred figures.
With natural light coming in from above, Phetchaburi's Khao Luang cave is one of the most atmospheric in the central region. The nearby Khao Bandai It cave has no natural light and is less interesting.