GNS Science said Zealandia has now been geologically mapped to its underwater edges at reconnaissance scale, completing coverage of the roughly 5 million-square-kilometre continent.
A 2023 Tectonics study of North Zealandia tied together seabed rock dating, magnetic anomalies, granite, sedimentary basins and volcanic belts, closing the last major regional gaps.
The case for continent status rests on four tests Zealandia meets: elevated crust above surrounding ocean floor, distinctive geology, continental crustal structure and a large, coherent area.
About 94% to 95% of Zealandia lies below sea level, but seismic data show 10-to-30-km-thick continental crust across much of it—far thicker and less dense than typical oceanic crust.
Scientists have argued since 2017 that Zealandia is a 4.9-million-sq-km continent that split progressively from Gondwana about 85 million years ago, even if school maps still usually show only seven continents.