How many goes have that had with the hulk and spider man movies?

Off the top of my head, rope to put down Gide lines in case you get silted out so you have something to follow to get out.

Also extra everything, if your open water diving and you run out of air (or other critial equipment failure) you can roll the dice on the bends by going straight to the surface, not so with cave diving; your just going to drown.