Tham Phi Hua To or Tham Hua Kalok
is located in Amphoe Ao Luk on Phi Hua To Mountains, which are surrounded by mangrove swamps.
The cave is accessible by the same route as Tham Lod Tai with its entrance not far beyond the canel to
Tham Lod Tai. From the entrance, the cave divides into 2 routes, the left one leading to a vast chamber
pierced by a shaft of light, while the right routeleads to a hall believed by archaeologists to have been
once a shelter for prehistoric people. Rock paintings can be seen within the cave. The paintings, 70 of
them, are painted in red and black and portray people as well as animals. The cave was named Phi Hua
To or Big-headed Ghost owing to the unusually large skulls discovered there. A large pile of shells were
also found in the cave.