Hup Pa Tat is a large valley with an area of about 48,000 square metres. The mountain range surrounding the valley is a limestone range. Part of it is Khao Huai Sok that connects with Khao Pla Ra, about 1 kilometre away. The way up to the cave is a margosa forest. Upon reaching the cave mouth you will see a dark cave. After a walk of around 100 metres, you will emerge from darkness and see the way down to the valley. Looking around you will see a limestone mountain surrounded by high cliffs. This enables sunlight to reach the ground only at midday. Therefore, the valley has higher humidity than other parts and this contributes to a wealth of flora. The thick jungle features gigantic shrubs of the genus Excoecaria that are similar to prehistoric trees.