<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/PumiceRaft.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/PumiceRaft.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/PumiceRaft.jpg?v=ap&w=980&h=551 800w" > A vast pumice raft floats in the tropical Pacific Ocean near Late Island in Tonga, captured on August 13, 2019, by the Operational Land Imager on Landsat 8. (NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey)

At a Glance The giant raft of floating stone was created by an underwater volcano near Tonga earlier this month.

Sailors reported being surrounded by pumice as far as the eye could see.

The pumice could carry millions of corals that could replenish the Great Barrier Reef.

A huge raft of pumice created by an underwater volcano is floating toward Australia, and it could help the Great Barrier Reef recover from bleaching.

The pumice raft is about 60 square miles — almost as big as Washington D.C. Scientists say it was formed earlier this month by an underwater volcano near Tonga, some 2,000 miles east of Brisbane, Australia, in the South Pacific Ocean.

As lava spewed from the volcano, it cooled into pumice stone , which is full of holes and can easily float, according to NASA.

Sailors first encountered the giant stone raft on Aug. 9 , according to the Smithsonian Institution’s Global Volcanism Program. The purser on a small ship reported being surrounded by pumice as far as she could see. She said the surface was about a foot deep and contained pieces larger than 30 inches in diameter.

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An Australian couple, Michael Hoult and Larissa Brill, encountered the raft while sailing a catamaran to Fiji on Aug. 16 , The Guardian reported.

“We entered a total rock rubble slick made up of pumice stones from marble to basketball size,” the couple wrote in a Facebook post.

"It was quite eerie, actually ," Brill later told CNN. "The whole ocean was matte — we couldn't see the water reflection of the moon."

Hoult said, "The rocks were kind of closing in around us, so we couldn't see our trail or our wake at all. We could just see the edge where it went back to regular water — shiny water — at night."

As this island of stone drifts toward Australia, it becomes home to countless marine creatures , Queensland University of Technology geologist Scott Bryan told the Australian Broadcasting Corporation.

"There's probably billions to trillions of pieces of pumice all floating together and each piece of pumice is a vehicle for some marine organism," Bryan said. "When it gets here, it'll be covered in a whole range of organisms of algae and barnacles and corals and crabs and snails and worms."

He said the millions of individual corals have the potential of finding new homes along Australia's coastline.

The pumice raft "is a natural mechanism for species to colonize, restock and grow in a new environment," he said. "It's just one way that nature can help promote regeneration."

“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 to the Great Barrier Reef,” Bryan told The Guardian.

(MORE: Great Barrier Reef Management Agency Sounds Alarm on Climate Change Effects)

Heat waves in 2016 and 2017 caused devastating coral bleaching and die-offs over two-thirds of the Great Barrier Reef.

Coral bleaching happens when warm water causes corals to expel the zooxanthellae algae living in their tissues. That causes the coral to turn white. Bleaching puts coral under more stress and makes it more likely to die.

Bryan said pieces of pumice should turn up along Australia's coastline in seven to 12 months.