There is an active underwater volcano off the Solomon Islands named Kavachi. A National Geographic team sent cameras into it and found stingrays, hammerheads and silky sharks in it.
This was unusual because the water is very hot and acidic. Scientists believe that they had to have mutated to be able to survive in an active volcano.
It last erupted in 2014 and is very active. It could erupt any minute and kill all the fish.