Phosphorous Cave was named after the phosphorous color of the light reflected from the surface of the water on the ceiling inside, and it is also called the blue cave, where sunlight shines through the water into the cave and thus there is a bright flash and luster that can be seen in the water and the walls of the caves, and the cave can be entered through By boat or by swimming, it is also possible to dive inside the cave and explore the colorful marine life under the waves.