Khao Wang Thong Cave, Khanom district, Nakhon Si Thammarat province, Thailand.
Khao Wang Tong Cave is the largest one of 3 caves of Khanom district. The other ones are “Khao Krot” cave and Phra temple cave ("Thamm Phra").
If you are not coming with a prearranged tour you may obtain the key for the padlock at the entrance gate for a small fee at the most nearby house. There is a knife switch for the caves electric lights on the inside on the right side from the entrance door in the fuses locker.
Following deeper inside you have to crouch one time and pass a rather confined passageway until you reach a large main cavern. The effort to get here is rewarded by a spectacular assemby of stalagtites and stalagmites in various shapes and sizes.