Dokutsu

This was a species of Shore Crab that seems to have evolved to live in the cave. Normally these crabs do not have the collection of hair on the pinches that this one has. The crab likely uses these hairs to capture edible particles in the water.

The high humidity in the cave combined with total darkness made taking a decent picture very difficult. Had my larger light not run out of battery's, these pictures likely would have turned out better.

To give you a sense of scale. This cavern was only about 3 feet high. I had to climb on my hands and feet through the water to advance further.

After being in the cave for about 30 minutes the confined space and thick air started to play tricks with my mind and began to induce a creeping feeling of panic. 

Having made it to the back of the cave, I figured it was time to turn around, which I did

Ginowan, Okinawa