Another must-see Grand Cayman scuba diving site is the big tunnels. The coral formations in the drop off are quite unique. It looks like Neptune himself scratched the area with his trident. With networks of canyons and crevasses, it is a home to the barrel sponge, the black coral, gray angels and eagle rays. The trinity caves are also located in this area. Here, one can see a system of four coral canyons that converge on the surface of a vertical wall.