Tham Sai is located in Khao Daeng in Prachuap Khiri Khan. It is a hill cave near Ban Khung Tanot, about 2.3km from the main road between Laem Sala and Sam Phraya beaches. You can rent lamps for a small fee from a shelter near the cave's mouth. A 280m trail leads up the hillside to the cave, which features a large single cavern. Be mindful of steep drop-offs in the cave.
- Open days
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday