The places sharks have to go to avoid humans these days… Scientists have discovered a population of sharks living inside an underwater volcano called Kavachi just off the coast of the Solomon Islands and east of Papua New Guinea in the South Pacific.

The National Geographic Society-funded team had been inching closer to the highly active volcano over four days, trying to gauge how safe it would be to dive in. Eventually, having not heard any tell-tale rumbles coming from the giant crater, they took the plunge so they could map the volcano's peak and study its chemical and geological make-up. And possibly even find life.

"Absolutely, we were scared," one of the team, Brennan Phillips told Carolyn Barnwell at National Geographic. "But one of the ways you can tell that Kavachi is erupting is that you can actually hear it - both on the surface and underwater. Anywhere within 10 miles (16 km) even, you can hear it rumbling in your ears and in your body."

Even so, they had every reason to be nervous. According to Barnwell, no one really knows how often the volcano erupts, and even when it's not spewing molten lava, ash, and steam into the surrounding water, it can be extremely dangerous for divers. "Divers who have gotten close to the outer edge of the volcano have had to back away because of how hot it is or because they were getting mild skin burns from the acid water," says Brennan.

To avoid the risk of burning flesh, Brennan and his team deployed submersible robots with underwater cameras into the volcano to be their eyes, and what they found was pretty extraordinary. Stingrays, jellyfish, hammerhead and silky sharks, all thriving in the hot, acidic, methane-ridden environment, despite all expectations.

"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," Brennan said.

Watch the footage above to see the sharks in their Sharkcano, and head to National Geographic to read the rest of the interview.