Wat Tham Sri Mongkhon is a Buddhist temple in Nong Khai which is home to Tham Din Phiang (fig.), a tunnel cave that has been formed by water erosion and which is situated in a valley within the temple's compound.

The cave is associated with the naga and is also referred to as Tham Phaya Naak. The path descending to the cave is hence lined on either side with statues of nagas coiling onto rocks.

Opposite of the cave's entrance is a balcony with a large gilded Buddha image overlooking the cave valley and seated in the pahng samahti pose. The entrance to the balcony is flanked by two Khmer style singh guardian lions.

Wat Tham Sri Mongkhon's large prayer hall is located on the hilltop near the main entrance gate of this temple complex.