Phraya Nakhon is a large cave on the ceiling with a opening allowing sunlight to go through the cave. The highlight of this cave is "Kareuhat Throne". It was built in the reign of King Rama V and it was workmanship of Princess Kajorn Charat Wong. It was created in Bangkok and then provided to Phraya Chonlayot Yothin to perform as a constructor. King Rama V came for the ceremony of mounting the gable-final with his own. On the right side of the stone wall, there are the signatures of King Rama V and King Rama VII. The letters are noticeably large and white. Kareuhat Throne is a landmark of Tham Phraya Nakhon and is the current Prachuap Khiri Khan Symbol.