Video Shows Sharks in Underwater Volcano

Hammerhead sharks
Hammerhead sharks swim close to Wolf Island at Galapagos Marine Reserve August 19, 2013. Hammerhead sharks were spotted in the Kavachi Volcano near the Solomon Islands in July of 2015. Jorge Silva/Reuters

National Geographic explorers made an unusual discovery in the Pacific Ocean's Solomon Islands: Brennan Phillips and his team dropped a camera into Kavachi, an underwater volcano, and recorded footage of two species of sharks and a stingray. The animals had made the volcano their home—but it's active and could, theoretically, erupt at any time, killing the wildlife within.

Phillips said the team was afraid as it approached the volcano but determined it was not currently erupting because it couldn't be heard or seen on the surface. "Nobody actually knows how often Kavachi erupts," Phillips told National Geographic's Explorers Journal.

Humans can't dive to Kavachi because of the temperature and the risk of acid burns, but the underwater camera can make it down safely, as can disposable robots and a Drop Cam. The Drop Cam caught a hammerhead shark, a silky shark and a stingray swimming through the volcano.

"These large animals are living in what you have to assume is much hotter and much more acidic water, and they're just hanging out," Phillips explained. "It makes you question what type of extreme environment these animals are adapted to. What sort of changes have they undergone? Are there only certain animals that can withstand it? It is so black and white when you see a human being not able to get anywhere near where these sharks are able to go."

It's so far unclear if the sea life picks up on volcanic activity in advance of an eruption and is able to escape, or if eruptions kill the creatures. Some smaller sea life, including jellyfish, snappers and small fish, were also caught on video in the volcano.