New Zealand and British scientists have discovered a new type of underwater volcano that emits lava that resembles a mass of foam and rises slowly to the surface of the sea.
Scientists say that previously, undersea volcanoes were deemed to be either explosive or effusive, depending on the strength of their eruptive force.
But the new class of eruption contains lava that is so packed with bubbles of gas that a buoyant foam is created that floats to the surface.
As it rises, the bubbles are released and lava falls to the ocean floor, with some pumice reaching the surface.
The new class of eruption will be named after the Maori god of the sea, Tangaroa.
The research was done at the Macauley volcano in the Kermadec Islands and was led by a team from Victoria University in New Zealand.
Scientists say the discovery is not connected with a raft of floating pumice found last year floating further north in the Pacific.