Sydney – It's a vast, strange land; its canyons and mountain ranges almost entirely unexplored, its creatures like something out of myth.
From what we know, it's beautiful – stretching more than a thousand miles from Savage Seamount across Three Kings Ridge, past swamp forests and volcanoes to the southern slopes.
Pigeons feed on cabbage trees in Zealandia, whales have beaks, and peanut worms crawl above light-less abysses.
In the last fraction of its long history, a relatively small band of humans has settled Zealandia's greatest mountain peaks, which they call the islands of New Zealand.
This place exists, though most of the 4.5 million square kilometres lie beneath the Pacific Ocean.
That shouldn't prejudice us against its significance, scientists argue in a paper that calls Zealandia "Earth's hidden continent."
"The large and the obvious in natural science can be overlooked," the researchers said in a newly published study in the Geological Society of America's journal.
As measured by human landmarks, Zealandia encompasses New Zealand and the island of New Caledonia about 2500 kilometres to the north.
It stretches beyond both and is two-thirds the size of Australia.
It would have been immediately recognised as a continent, the researchers argue, if Earth's peaks and valleys "had first been mapped in the same way as those of Mars and Venus" – with no pesky water to obscure the truth of rocks.
"If we could pull the plug on the oceans it would be clear to everyone we have mountain chains and a big high-standing continent above the ocean crust," lead author Nick Mortimer, a New Zealand government geologist, told Reuters.
Instead, the researchers say, Zealandia has been written off for decades "as an amalgam of continental fragments and slivers": the wreckage of an ancient supercontinent, Gondwana, which disintegrated when dinosaurs walked the Earth.
We know Gondwana's orphaned survivors as Africa, South America, Australia and Antarctica.
If Mortimer and his team have their way, Zealandia would be added to that list.
Jut like its former neighbours in Gondwana, the mass that became Zealandia drifted off tens of millions of years ago, the teams says. It had the misfortune of being stretched, thinned and 94 percent of it submerged – so that when humans came along, they mistook it for the ocean crust.
"The accuracy and precision of seafloor mapping have improved greatly over the past decades," the researchers say. They say Zealandia meets all the definitions of a continent: a huge, coherent mass that sits above and is distinct from the ocean crust.
Zealandia has all the right rocks. It has "interconnected and throughgoing geological provinces," the researchers say.
Calling it what it is, the scientists say, would mean "much more than just an extra name on a list."
It would help us understand the earth beneath our feet – and the parts of it that are not – by exposing a continent unlike any other to more research.
And yet, notes BBC News, "there is in fact no scientific body that formally recognises continents."
That means Zealandia will become a continent only if members of its minority population – human beings – decide to call it one.