How strange, this desire to leave our mark on every part of the planet. But this island is unlikely to feature in a standard tourist brochure. The view atop the mountain boasts black sand, waves and a seemingly endless sea. The backside of the mountain encircles a large blue-green lake - tinted sulphurous yellow - which spills into the sea at high tide. We stop for photos but are beset by thousands of flies. There's a chill wind and a light rain is falling.

Down below, parts of the island are split into long, shallow channels that have become breeding grounds for large flocks of gulls. The cracked mud plain is dotted with red, yellow and black rocks that are stained white with bird droppings.

Life takes shape so quickly where there was nothing before. Standing here is like watching as a continent is born. "For a geologist and a volcanologist and pretty much any human being, this is a very exciting process because it's not often that we can actually see very dramatic changes in the surface of the earth," says University of Tasmania volcanologist Jocelyn McPhie.

"We are watching new land being created. This is essentially how the continents are made. Long in the future, what is a tiny speck in the southwest Pacific could be part of a much more substantial land mass."

This speck rose from the sea in January between two established uninhabited volcanic islands - Hunga Tonga and Hunga Ha'apai - joining them together into one larger land mass. The island was created by a newly awakened volcano, which rumbled to life in December and began erupting from two vents: one on Hunga Ha'apai and the other underwater about 100 metres offshore.

Local fishermen saw dense ash and rocks spewed some 400 metres into the sky. Plumes of steam and gas soared more than a kilometre in the air, prompting the cancellation of some international flights. The blasts destroyed the trees on Hunga Ha'apai, which now looks like a relic from a bushfire.

The island was formed by pulverised magma, which exploded out of the vents in small pieces and dropped into the sea. Those tiny deposits of volcanic ash gradually built up on top of each other, in such quantity that they rose up through the surface of the water. "Just imagine you have an unlimited supply of fine particles being blown out of a vent in such large volumes that they can actually build land," Professor McPhie says.

"Most of that island is made up of very small particles, about the size of the sand grains you find on a beach, and are very easily washed away in storms. So we usually don't expect these sorts of little islands, that are mainly made of fine ash, to last."

If the volcano starts to produce lava, that fine ash might solidify into rock, she says. Otherwise, the island will probably wash away within years.

There are already signs of decay here. The ground is dangerously unstable in parts. Waves are eating away at the edges of the mountain. We watch as part of the cliff above the lake cracks and tumbles into the water. Tonga's Ministry of Lands and Natural Resources reportedly warned in May that the island was dangerous because a volcanic eruption was possible at any time.

Officials in the Kingdom of Tonga have declined to name the island, because they fear the fragile land mass will soon disappear. Some locals have reportedly proposed naming it after Tongan Prime Minister Akilisi Pohiva, a pro-democracy campaigner and the first commoner elected to lead the constitutional monarchy. Others suggested the name of Valerie Adams, an Olympic shot-put champion whose mother is Tongan.

On the unnamed island's western tip is a crumbling cave, where former British entrepreneur Ian Argus Stuart slept while spending 11 days on the island in May. He survived on squid, bird's eggs and coconuts that washed ashore, as part of a "castaway" experience organised by travel company Docastaway, , which also helped arrange Fairfax Media's trip.

Crabs climb over the loose mud walls of the cave. Outside, the tides have dragged in discarded soft drink bottles, sandals and life buoys.

We swim in the warm waves while fisherman Futa Fuko brings Kerryelle close to shore. He used to drive his small boat through this patch of once-empty ocean - now he has to go the long way around. "It will be sad if the island disappears because it's a new thing to see," he says.

Our day on the newest part of the planet is over. The island recedes from view as we putter away. So new it doesn't even bear a name. What would you call it, I ask Fuko. "I'd name it God's fire," he says.

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