"The source of an enormous floating mass of pumice spotted this week in the South Pacific Ocean off the coast of New Zealand has been discovered: NASA satellite images and other sleuthing science have pinpointed an erupting undersea volcano called the Havre Seamount as the culprit."
"On Aug. 9, the HMNZS Canterbury ship observed the floating pumice 'island' — measuring a whopping 300 miles (482 kilometers) in length and more than 30 miles (48 km) wide — along a voyage from Auckland to Raoul Island, New Zealand. A maritime patrol aircraft, RNZAF Orion, had seen the weird mass and reported it to this Royal New Zealand Air Force ship. Soon after, the HMNZS crew saw the thick mass of porous rocks.
'The rock looked to be sitting two feet above the surface of the waves, and lit up a brilliant white colour in the spotlight. It looked exactly like the edge of an ice shelf,' said Lieutenant Tim Oscar, a Royal Australian Navy officer, in a statement."