It is "unbearably hot and humid," according to Issun. Water leaks into the dragon from pores in the walls of the dragon's body. There are many treasures in clams that can be found throughout the dragon. There is also evidence that the Water Dragon ate someone alive in a small chamber, which has the remains of a small boat, human, and fish. The Dragon Orb is tangled in muscles in a certain room, and digestive liquid can be found not too far away. It is possible that the room with the acid is the stomach of the Water Dragon.
The Fox Rods, which the Water Dragon consumed, are in the dragon's stomach, along with the Dragon Orb.