A large pumice raft is slowly drifting in the Pacific Ocean believed to be the result of an underwater volcanic eruption in early August near Tonga.

The size of the pumice raft is around 150 sq km, the equivalent of 20,000 football fields, according to a BBC report [2].

Pumice is a light coloured volcanic rock produced when lava goes through rapid cooling and loss of gases, enabling it to float in water.

Samples of the pumice were collected by Australian sailors who sailed into the raft while on their way to Fiji.

In a facebook post [3], they warned vessels in the area to steer clear of the pumice which varied in sizes “from marble to basketball”. They said the raft  covered the water “went as far as we could see in the moonlight and with our spotlight”.

The samples were sent to researchers at the Queensland University of Technology (QUT) in Australia.

QUT Geologist, Associate Professor Scott Bryan, said “at the moment there are more than a trillion pieces of pumice all floating together but over time it will break up and disperse across the area”.

He told the BBC pumice masses like this could be seen in the region once every five years, and is reported over time, “usually as islands in the middle of the ocean that people encounter but then can't find again”.

The pumice is currently drifting westwards towards Fiji and on its current path, is expected to pass New Caledonia and Vanuatu and forecast to reach Australia where it could boost the damaged Great Barrier Reef.

Pumice – home to marine life

The pumice raft would likely become home to marine life said University of Tasmania’s Dr Martin Jutzeler.

"A lot of life... can attach themselves to the pumice and be transported thousands of km away. So, it's a way to renew ecosystems somewhere, but it also can introduce invasive species."

It possibly could reach Australia in a year's time, but we don't know if it could even last, he said.

If the pumice does reach Australia, Associate Prof Bryan said it could restock the Great Barrier Reef, which suffered coral bleaching events in 2016 and 2017.

"Based on past pumice raft events we have studied over the last 20 years, it's going to bring new healthy corals and other reef-dwellers."