This floating pumice raft in the Pacific could help save the Great Barrier Reef


The Great Barrier Reef is set to receive a restocking of new coral in eight months thanks to a pumice raft which is estimated to rival the size of Manhattan.

Australian surfers sailing to Vanuatu on a catamaran have stumbled across an extraordinary phenomenon - a floating mass of pumice rocks.

ROAM crew Michael and Larissa Hoult reported the sighting last week and described the event as a "rubble slick made up of rocks from marble to basketball size such that water was not visible."

Earlier this month, NASA Earth Observatory recorded imagery of the vast pumice raft floating in the tropical Pacific Ocean near Late Island in the Kingdom of Tonga.

It has been estimated in size to be similar to that of Manhattan - or approximately the size of more than 20,000 football fields.

Some of the pumice.
Some of the pumice.

And the good news is that it could help solve a host of problems at The Great Barrier Reef.

According to the Queensland University of Technology, the raft should hit Australian shores in about eight months, "bringing with it billions of marine animals who attach themselves along the way".

Pumice rocks are full of holes and cavities, and they easily float.

QUT's Professor Bryan has been following the pumice raft’s voyage since the eruption with the help of QUT spatial scientist Dr. Andrew Fletcher.

“This is a potential mechanism for restocking the Great Barrier Reef," Professor Bryan said.

“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.”

This raft is cool, but you know what's cooler? It made its own weather, it's helping trillions of sea critters invade Australia, and the volcano that made it has no name, but if it now gets one, it'll be decided by the Kingdom of Tonga.

Me, for @Gizmodo

— Dr Robin George Andrews 🌋 (@SquigglyVolcano) August 26, 2019

A Raft of Rock #NASA

— NASA Earth (@NASAEarth) August 23, 2019

If anyone has additional information about this submarine eruption or the pumice rafts, please let us know. GVP will be working on gathering everything we can to write this up in our reports so there's a record for future reference.

— Global Volcanism Program (@SmithsonianGVP) August 16, 2019

If you like pumice rafts made by undersea eruptions (and who doesn’t), today was a banner day for you! My post: and @NASAEarth

— Erik Klemetti (@eruptionsblog) August 23, 2019

QUT experts said the pumice comes from an unnamed but only recently discovered underwater volcano that satellite images reveal erupted probably on 7 August.

This volcano last erupted in 2001.

Pumice Raft track map
Pumice raft track map.

Volcanologist Erik Klemetti of Denison University has written on a blog that “pumice rafts can drift for weeks to years, slowly dispersing into the ocean currents."

"These chunks of pumice end up making excellent, drifting homes for sea organisms, helping them spread ...The erupted pumice means this volcano erupts magma high in silica like rhyolite.”

NASA’s Terra satellite detected the mass of floating rock on 9 August.

'It went as far as we could see'

The Hoults have since arrived in Fiji but have been busy providing samples and details of their encounter to QUT.

The couple said they reduced their speed when they first started "seeing some floating rocks of random sizes (marbles to tennis balls).

And shortly afterwards they experienced a "faint but distinct smell of sulfur".

Then they started to see and strike larger floating rocks.

"We took down all sail. Allowing the boat to continue on bare poles ... as we could no longer smell the sulfur we assumed we would be soon clear of the rubble so elected to continue at slowest speed," they posted.

At about 7am on 15 August they said they entered "a total rock rubble slick made up of pumice stones from marble to basketball size".

"The waves were knocked back to almost calm and the boat was slowed to 1kt," their Facebook post said.

"The rubble slick went as far as we could see in the moonlight and with our spotlight.

"We made a turn to starboard and managed to sail clear of the rubble slick under Staysail.

"We had entered it approx 200m and the edge could be made out in the partial moonlight back to the
NE. It was extensive in all other directions."

Good news for Great Barrier Reef

Professor Bryan said the sighting is good news for the Great Barrier Reef.

“At the moment the pumice will be bare and barren but over the next few weeks it’s going to start getting organisms attached to it,” Professor Bryan said.

“Then they’re going to grow and diversify, to ultimately wash up here in Australia.

“It’s the right timing. So it will be able to pick up corals and other reef-building organisms, and then bring them into the Great Barrier Reef.

“Each piece of pumice is a rafting vehicle. It’s a home and a vehicle for marine organisms to attach and hitch a ride across the deep ocean to get to Australia.”

Stay up to date with SBS NEWS

  • App
  • Subscribe
  • Follow
  • Listen
  • Watch