Taken from the boat, the entrance to the underground river is the dark area on the rocks beyond. The tour is usual during low tide so there will be enough headroom from the boat and the stalactites that drop down from above. On the right is a measuring stick to indicate if there is enough room for us to go through. At a very high tide this opening closes. This underground river is not like those caverns in the United States that is fully lighted. Our guide carries a battery powered light to point at special places inside the cave. It is really not adequate lighting for photography. Inside althought the cave is about 50 to 60 feet high the stalactites drop down almost to the level of your head. Bats are hanging over the top sleeping. At night, these bats go out of the cave.