A group of geologists believes New Zealand and several surrounding islands, including New Caledonia, should be reclassified as part of an eighth continent called Zealandia, rather than be grouped with Australia in the Australasia region.

As the islands are connected by submerged continental crust, which is separate and distinct from Australia and Antarctica, the geologists argue that they should form their own continent — even if 94% of that 1.9 million-square-mile land mass (approximately the area of greater India) is underwater.

The geologists, who hail from New Zealand, Melbourne, New Caledonia and Sydney, spent more than two decades gathering enough data to make the case for Zealandia. They collated their findings in a study called “Zealandia: Earth’s Hidden Continent,” published in the Geological Society of America’s journal, GSA Today

“Zealandia illustrates that the large and the obvious in natural science can be overlooked,” the researchers say in the conclusion of their study. “Based on various lines of geological and geophysical evidence, particularly those accumulated in the last two decades… Zealandia is not a collection of partly submerged continental fragments but is a coherent 4.9 Mkm2 continent.”

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Write to Kate Samuelson at kate.samuelson@time.com.