In January 2015, researchers lowered a baited camera into Kavachi during a rare lull and recorded scalloped hammerhead and silky sharks, fish and gelatinous animals inside its shallow crater. The water was warm, acidic and sulfur-rich, but the footage does not show sharks enduring an eruption or prove they permanently live, hunt or predict eruptions there.
Key takeaways
- Kavachi is a highly active submarine volcano in the Solomon Islands, with its summit roughly 20 meters below sea level.
- A 2015 expedition filmed scalloped hammerhead and silky sharks inside the crater during a quiet interval.
- Scientists measured water in the crater that was warmer and more acidic than the surrounding ocean and found evidence of sulfur-cycling microbes.
- The observation does not prove that sharks remain in the crater during an eruption or that a permanent shark population lives there.
- No published evidence shows that sharks use their ampullae of Lorenzini to detect volcanic chemistry or forecast an eruption.
Where is Kavachi—and why is it called a “Sharkcano”?
Kavachi lies in the southwest Pacific, south of Vangunu Island in the Solomon Islands. It is a shallow submarine volcano associated with the tectonically active region where the Indo-Australian Plate descends beneath the Pacific Plate. Its eruptions can drive hot gas, ash and fragmented rock through seawater, sometimes discoloring the sea surface or briefly building small islands that waves later erase.
The nickname “Sharkcano” followed a 2015 research expedition and a 2016 scientific paper describing sharks recorded inside Kavachi’s crater. The name is memorable, but it can also create a false picture. Researchers did not film sharks swimming through molten lava or an explosive eruption. They entered the crater during a rare lull in activity, when instruments and cameras could be deployed with less risk.
What the 2015 expedition actually found
During the January 2015 expedition, scientists mapped Kavachi, sampled the water and lowered a baited autonomous camera through approximately the upper 50 meters of the water column. Video from the crater showed reef fish, zooplankton and gelatinous animals. It also captured two kinds of shark: a scalloped hammerhead and a silky shark.
That was a striking result because the crater is not a stable coral-reef habitat. Kavachi is repeatedly disturbed by volcanic activity, and its plume can expose animals to rapid changes in temperature, acidity, turbidity and dissolved chemicals. The footage demonstrated that large, mobile predators were willing to enter the crater under the conditions present during the survey.
It did not establish how long either shark stayed, whether the same individuals returned, or whether sharks were present during an eruption. The camera was baited, so the possibility that food odors influenced their approach must also be considered. “Sharks were observed inside the crater” is supported; “sharks permanently live in an erupting volcano” is not.
How extreme was the water?
Measurements showed that Kavachi’s crater water differed sharply from nearby seawater. In the volcanic plume, researchers recorded a temperature anomaly of about 13°C above the surrounding water and a pH difference of roughly 1.9 units. Because the pH scale is logarithmic, that represents a substantial increase in acidity. The team also documented carbon dioxide-rich gas, turbid water and sulfur-rich fluids.
Those values describe sampled plume conditions, not every part of the crater at every moment. A mobile shark can move through a patchy environment and avoid the harshest zones. Calling the entire crater “boiling acid” would be inaccurate: the animals were swimming in seawater affected by volcanic inputs, not in a pot of uniformly boiling liquid.
Why would sharks enter Kavachi?
The honest answer is that scientists do not yet know. Small fish and other potential prey were present, and bait on the camera may have attracted curious predators. Sulfur-cycling bacteria were detected in crater samples, but the study did not demonstrate a complete food chain in which volcanic microbes directly caused fish schools to gather and sharks to hunt them.
Silky sharks are wide-ranging oceanic predators, while scalloped hammerheads can travel through coastal and offshore habitats. Their appearance at Kavachi may reflect normal exploration by highly mobile animals rather than a special population adapted exclusively to volcanic water. Repeated surveys, tracking tags and measurements taken across different stages of volcanic activity would be needed to test that idea.
Can sharks sense an eruption before it happens?
Sharks possess sensory organs called the ampullae of Lorenzini, which detect extremely weak electric fields. This ability helps sharks locate prey and interpret electrical information in their surroundings. Laboratory studies have also recorded responses to abrupt temperature changes, but the established biological function of the organs is electroreception.
No evidence from the Kavachi expedition shows that sharks used these organs to analyze sulfur, acidity or other volcanic chemicals. Nor did the study follow sharks before an eruption and document a predictive escape. It is reasonable to expect mobile animals to avoid conditions they find harmful, but turning that expectation into a claim that sharks can forecast eruptions goes beyond the data.
Is Kavachi still active?
Yes. The Smithsonian Institution’s Global Volcanism Program reported intermittent yellow-green discolored water above Kavachi during May and June 2026, based on satellite observations. Such discoloration can indicate submarine activity or material suspended in the water. It is a current sign of the volcano’s restlessness, but it is separate from the shark footage, which was recorded in January 2015.
Kavachi’s continuing activity is precisely why scientists must treat it as a dynamic habitat. A quiet survey day, an active degassing phase and an explosive eruption are biologically different situations. The “Sharkcano” story is most interesting when those differences are kept intact.
Frequently asked questions
Do sharks live inside an active volcano?
Sharks were filmed inside Kavachi’s active volcanic crater during a lull in activity. That confirms their presence at that time, but it does not prove they are permanent residents or remain there during eruptions.
What shark species were seen at Kavachi?
The 2015 baited-camera survey recorded a scalloped hammerhead shark and a silky shark, along with smaller fish and gelatinous animals.
Were the sharks swimming in lava?
No. They were swimming in seawater inside the submerged crater. The water was affected by volcanic gases and fluids, but the survey took place during a rare pause in eruptive activity.
Can sharks predict volcanic eruptions?
There is no published evidence from Kavachi showing that sharks predicted an eruption. Their electroreceptors detect weak electric fields, but claims that they read volcanic chemistry and leave before an eruption remain speculative.