Introducing Zealandia - updated

Some geologists argue that this area should be acknowledged as our world's eighth continent.  It has not previously been recognized because most of it is under water.

Geophysical data suggest that a region spanning 5 million square kilometres, which includes New Zealand and New Caledonia, is a single, intact piece of continental crust and is geologically separate from Australia...

However, there is no international body in charge of designating official continents, and so the researchers must hope that enough of their colleagues agree to recognize the landmass. Otherwise, their proposal could remain more of a theoretical wish than a radical reshaping of what every child has to learn in geography class...

...Zealandia began to peel away from the supercontinent of Gondwana starting about 100 million years ago. The rift gave Zealandia its independence, but it also pulled and thinned the crust, causing the area to sink, and dooming most of it to a watery existence. Today, only about 6% of it remains above water, as New Zealand and New Caledonia...

There is no widely accepted definition of a continent, and geographers and geologists differ on the question. (Geographically, Europe and Asia are considered separate continents, whereas geologists consider them the single landmass of Eurasia.)

Reposted to add more info and another map:

On Wednesday researchers shared findings from their two-month-long expedition, one of the first extensive surveys of the region, announcing fossil discoveries and evidence of large-scale tectonic movements.

“The discovery of microscopic shells of organisms that lived in warm shallow seas, and spores and pollen from land plants, reveal that the geography and climate of Zealandia was dramatically different in the past,” said Prof Gerald Dickens of Rice University...

“[The research] has big implications for understanding big scientific questions, such as how did plants and animals disperse and evolve in the South Pacific? The discovery of past land and shallow seas now provides an explanation: there were pathways for animals and plants to move along.”

More at the link.