A science team has an exciting mission underway. They’re somewhere in the eastern Indian Ocean, where their goal is to find out more about hydrothermal activity. Now, their journey takes them to Kavachi, an underwater volcano near the Solomon Islands – a country made up of hundreds of islands and which lies to the east of Papua New Guinea. However, when the researchers arrive at their destination, they aren’t prepared for what they find.
The Solomon Islands were once infamous among Europeans for apparently being home to notoriously violent indigenous people. And it’s thought that these locals were, naturally, aggrieved by the arrival of colonialists and the slave trade.
But besides that, the island nation also has an interesting geological history. And that’s why the research team, led by National Geographic Society/Waitt Grants Program grantee Brennan Phillips, went there in 2015. They initially wanted to map Kavachi’s peak as well as gather other important information about the volcano and its watery surroundings.
Kavachi is also known as Rejo te Kavachi, or “Kavachi’s Oven.” And it’s a moniker that’s well deserved. “Divers who have gotten close to the outer edge of the volcano have had to back away because of how hot it is,” Phillips told National Geographic. “They were getting mild skin burns from the acid water.”
This heat, then, naturally affected the kinds of instruments that the researchers could use to gather their information. Consequently, they used expendable robots to investigate the volcano, as well as robust underwater cameras and a “drop cam” designed especially for deep dives.
“Absolutely, we were scared,” Phillips admitted to 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 even, you can hear it rumbling in your ears and in your body.”
Footage uploaded to YouTube by National Geographic shows the scientists dropping their specialist equipment into the water. Then, the camera sinks quickly, descending 147 feet through billowing clouds of ash. Amazingly, the color of the water changes quickly – from blue to green and orange. This extraordinary visual effect is caused by diminishing levels of iron and sulfur in the water.
Sinking further into the water, the camera subsequently lands on a ledge and captures something stirring in the murk. At one point, a large stingray appears, flapping its wings against the side of the caldera. And the scientists are, quite rightly, astonished. Because how could anything so large ever survive at this temperature and acidity?
But that’s not all. Incredibly, the footage shows a shark swimming slowly through the gloomy water – and it’s not alone. Indeed, by the end of their observation, the researchers had spotted sharks of two different species – a silky shark and a scalloped hammerhead shark – along with the sixgill stingray.
There was other marine life there, too. Yes, besides sharks were snapper fish, jellyfish and other types of underwater animals. Understandably, the researchers were stunned by what they’d seen inside the submerged volcano. “When it’s erupting, there’s no way anything could live in there,” Phillips asserted.
And so began the process of figuring out how something could live in a volcano caldera. Firstly, Phillips contemplated what the animals might get up to when Kavachi is particularly active: “Do they leave? Do they have some sort of sign that it’s about to erupt? Do they blow up sky-high in little bits?”
At one time scientists believed that subaquatic volcanoes release lava into the water in steady streams. Now, however, we know that such volcanoes only erupt periodically in “pulses.” What’s more, Phillips said that when these eruptions occur, they end up “spewing hot lava, ash and steam up in to the air.”
Phillips was also curious as to whether the animals living in Kavachi evolved to suit to their unique habitat. “It makes you question what type of extreme environment these animals are adapted to,” he wondered. “What sort of changes have they undergone?”
Not only that, but Phillips also pondered whether there could be other animals that are living near Kavachi. Such creatures, he reasoned, would be able to survive and perhaps thrive in the hot and acidic environment. “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,” he said. “Are there only certain animals that can withstand it?”
However, the reality is that researchers aren’t going to know how the animals react to volcanic eruptions until the next one happens. And, unfortunately, experts are currently at a loss as to how to predict when Kavachi will next blow. Indeed, Phillips admitted to National Geographic, “Nobody actually knows how often Kavachi erupts.”
The team aren’t, however, going to let that deter them. In fact, for their next set of experiments they are considering combining observations on the surrounding geology of Kavachi with a study of the incredible creatures surviving in the caldera.
“It would be very interesting to pair observations of animal activity, such as the sharks, with actual eruptions of the main peak,” Phillips said. Indeed, he wants to know how the creatures will react when the going gets tough. “Do they get an early warning and escape the caldera before it gets explosive, or do they get trapped and perish in steam and lava?” he wondered.
And, according to National Geographic, this would involve setting up deep-sea cameras on Kavachi itself. Nearby, the team would establish an observatory to record changing levels in seismic activity and, hopefully, catch a volcanic event in action. This, crucially, would allow them to learn how local wildlife respond to eruptions.
Phillips has yet to find out whether the animals might know when an eruption is coming. However, some online commenters have put forward their own theories. For example, one suggested, “Most underwater animals feel vibrations easily, so they probably know when the volcano is about to erupt.”
Yet whatever the true explanation, it’s nevertheless amazing to find life in such harsh conditions. And, what’s potentially even more impressive is the possibility that these creatures are able to know when to evacuate in the event of an eruption. If true, it’d be an amazing example of the resourcefulness and adaptability of marine life.