A MYSTERIOUS volcanic island that suddenly burst from the Pacific Ocean is now teeming with life.

The miracle outcrop known as Hunga Tonga has only existed for four years, yet is populated by hundreds of seabirds and flowering plants whose seeds were dropped there in bird poo.

7 Experts found hundreds of seabirds called sooty terns nesting in Hunga Tonga's cliff gullies Credit: Dan Slayback

Hunga Tonga emerged from a hidden underwater volcano lodged between two existing islands of the Kingdom of Tonga in the South Pacific.

It still has no official name, but locals have branded it Hunga Tonga-Hunga Ha'apai, or "Hunga Tonga" for short.

The island is only the third volcanic pop-up like this to have arisen in the last 150 years, and Nasa has been attempting to uncover its mysteries since it arose from the sea in 2015.

Most research has involved taking snaps from satellites or aircraft, but space boffins recently got a rare chance to explore Hunga Tonga on foot.

7 The island didn't exist four years ago Credit: NASA Scientific Visualisation Studio

7 But it quickly sprouted from the Pacific following an underwater eruption Credit: NASA Scientific Visualisation Studio

7 Plantlife growing on Hunga Tonga that experts think were seeded by bird poo Credit: Dan Slayback

"We were all like giddy school children," scientist Dr Dan Slayback from Nasa's Goddard Space Flight Centre told the space agency's Earth Expeditions blog.

"Most of it is this black gravel, I won't call it sand – pea sized gravel – and we're mostly wearing sandals so it's pretty painful because it gets under your foot."

On the island, experts took GPS measurements and used drone surveys to map the landscape.

They found an army of seabirds called sooty terns nesting in Hunga Tonga's cliff gullies, as well as flowering plants that they think were seeded by bird droppings.

7 Hunga Tonga sits around 19 miles southeast of Tonga

7 The island joins two, smaller islands together Credit: Woods Hole

7 December 29, 2014 image showing the ongoing undersea eruption at Hunga Tonga Credit: Nasa

A solitary barn owl even passed overhead while they were there.

Researchers said the trip shed new light on rare volcanic islands – though they don't know how long Hunga Tonga will last before it has eroded to nothing.

"The island is eroding by rainfall much more quickly than I'd imagined," Dr Slayback said.

"We were focussed on the erosion on the south coast where the waves are crashing down, which is going on. It's just that the whole island is going down, too."

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Scientists warned last year of an underwater supervolcano that threatens to blow and kill 100million people after they found a six-mile-wide lava dome near Japan.

A similar underwater eruption wiped out 90% of Earth's ocean species in an event known as the Great Dying 250 million years ago.

You can read our guide on what causes volcanoes to erupt and how they are formed by clicking here.

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