Somewhere beneath the waters of the tropical Pacific Ocean, likely around the island of Tonga, a volcano recently erupted. The proof lies in a sprawling raft of extremely lightweight volcanic rock called pumice, which is so porous that it floats. NASA posted satellite images of the drifting mass on Aug. 23, though the geologic display was first spotted in mid-August.
“Many of the world’s volcanoes are shrouded by the waters of the oceans,” wrote NASA. “When they erupt, they can discolor the ocean surface with gases and debris. They also can spew masses of lava that are lighter than water.”
As of Aug. 13, the raft, in total, appeared larger than the island of Manhattan, which is about 23 square miles in size. Pumice is created during explosive volcanic eruptions, wherein the gas trapped molten rock explodes out of the scorching material in a violent pressure release.
Adventuring sailors on a catamaran met the great pumice raft up close. They encountered floating pumice ranging in size from marbles to basketballs, some of which jammed their rudders. The team also noted the ominous smell of sulfur wafting through the air, and posted their experience on Facebook.
The oceans will incrementally disperse this fleeting geologic wonder, but it’s common for some marine life to hitch a ride on the floating stones, and journey across the globe.