In July 2012, the submarine volcano Havre, located in the Kermadec arc north of New Zealand, erupted, releasing enough pumice—light, porous volcanic rock—to form a floating raft covering 400 square kilometers on the Pacific Ocean's surface in a single day. The eruption occurred underwater, between 900 and 1220 meters in depth, across at least fourteen distinct volcanic vents. At the time, volcanologists were unaware that Havre was an active volcano. It was only later, through satellite imagery, that a plume and gray water were identified as originating from the eruption on July 19, 2012. Three weeks later, on August 9, a New Zealand Air Force Orion patrol plane spotted a white area while flying between Samoa and New Zealand. The pilots relayed the discovery to the warship HMNZS Canterbury, which crossed the raft the same day, about 160 kilometers southwest of the island of Raoul. The crew measured a pumice layer about 0.6 meters thick, one kilometer wide, stretching as far as the eye could see. They collected samples directly from the ship’s water filters before New Zealand geologists traced the eruption’s origin back to Havre using seismic data from July 17 and 18. Pumice floats because it contains numerous air bubbles, making it less dense than water. It forms when gas-rich magma cools rapidly upon contact with cold water, trapping microbubbles inside the rock. This porosity reduces its density so much that it can float for years before eventually sinking as it absorbs water. On Havre, more than 75 percent of the erupted material took this floating form, while the rest became lava or ocean-floor deposits. Scientists estimate the total volume of rhyolitic magma released during the eruption to be approximately 1.5 cubic kilometers. The eruption is officially classified as a VEI-1, the lowest level on the Volcanic Explosivity Index, by the Smithsonian Institution. However, the volume of material released aligns more closely with a VEI-5, suggesting that the scale may not be well-suited for measuring deep submarine eruptions. The pumice raft did not remain stationary. By August 19, 2012, it had spread to cover about 270,000 square kilometers of the Pacific Ocean, pushed by ocean currents and wind. The pumice continued to drift for months, some fragments dispersing into thin strips too small to be detected by satellites. Eventually, parts of the raft washed up on the coasts of Tonga and northern New Zealand, while others reached the east coast of Australia nearly a year after the eruption. Researchers have identified more than eighty different marine species that colonized these floating pumice rocks, ranging from barnacles and corals to bryozoans and various algae. This biological phenomenon is not just a curiosity for scientists. Pumice, resistant to erosion and indestructible in saltwater, acts as an effective carrier for marine life, enabling their long-distance dispersal. In 2015, an expedition using an autonomous underwater vehicle mapped the Havre caldera's floor, revealing giant pumice blocks up to 9 meters in diameter. This discovery confirmed that the Havre eruption remains the largest silicic eruption in deep water ever documented.