For nearly four centuries, an entire continent lay unnoticed beneath the waves of the southwest Pacific. Known today as Zealandia, this vast underwater landmass larger than India and almost two-thirds the size of Australia spent most of human history missing from maps, overlooked by textbooks and absent from scientific agreement. Only in recent years has it finally claimed recognition as Earth’s long-lost eighth continent.
In 2017, a team of geologists formally declared Zealandia a continent after decades of accumulating clues. Their finding stunned the global scientific community. Zealandia possesses a continental crust, distinct tectonic boundaries, and a clear geological lineage that traces back to the supercontinent Gondwana. Yet 94 percent of it lies submerged beneath the ocean, making it the most elusive of Earth’s landmasses.
The rediscovery of Zealandia is more than a scientific milestone. It highlights the limits of surface-based exploration and reveals how much of the planet especially beneath the ocean still remains unknown.
The continent science nearly overlooked
The modern case for Zealandia came together in a landmark 2017 publication in GSA Today by researchers from GNS Science, New Zealand’s Crown Research Institute. The study concluded that Zealandia satisfies all major criteria for a continent: significant area, a distinct geological structure, thicker crust than oceanic plates and clear boundaries.
“Zealandia is not just a collection of continental fragments,” the authors wrote. “It is a coherent continent, and should be recognized as such.”
Its invisibility was largely a matter of depth. Much of Zealandia lies more than 6,500 feet below sea level, deep enough to escape traditional geological mapping. Only after advances in satellite gravity measurements, detailed seafloor mapping and deep-ocean drilling did its full shape come into focus. BBC Future estimates the region spans about 4.9 million square kilometers.
Unlike other continents, Zealandia’s crust is unusually thin about 20 kilometers, compared to the typical 30–45 kilometers elsewhere. This thinness may explain why the landmass sank after breaking away from Gondwana roughly 85 million years ago.
Hints stretching back centuries
The idea of a hidden southern continent dates back to early European exploration. In 1642, Dutch navigator Abel Tasman sailed in search of the mythical Terra Australis. Although he never found that hypothetical continent, his route took him along the coast of New Zealand skimming just above what we now know is a submerged continental shelf.
For centuries, mapmakers filled the unknown south with speculative landmasses, reflecting both scientific curiosity and geographical mystery. Though mistaken, these early depictions foreshadowed the discovery modern science would eventually confirm.
By the late 19th century, scientists were already proposing the idea. In 1895, Scottish naturalist Sir James Hector suggested that New Zealand was the visible edge of a much larger submerged continent. His findings, published in the Transactions and Proceedings of the Royal Society of New Zealand, were accurate but largely ignored.
The term “Zealandia” finally gained prominence in 1995 when U.S. geophysicist Bruce Luyendyk used it to describe the submerged plateau surrounding New Zealand. Over the next two decades, research accelerated, fueled in part by strategic incentives: proving Zealandia’s continental identity could allow New Zealand to extend its maritime economic rights under the United Nations Convention on the Law of the Sea.
Drilling into a drowned world
A key breakthrough came in 2017 through the International Ocean Discovery Program. Scientists drilled six deep-ocean sites across Zealandia, extracting sediment cores that reached nearly 4,100 feet beneath the seafloor. These cores contained microfossils, pollen grains and chemical signatures of shallow marine environments evidence that parts of Zealandia were once above water.
Findings of terrestrial life added to the picture. Fossil remains of dinosaurs, including a sauropod and an ankylosaur, have been discovered on New Zealand and the Chatham Islands. These fossils date to a period after Zealandia separated from Gondwana, indicating that substantial portions of the continent remained above sea level long enough to sustain ecosystems.
The timing of Zealandia full submergence remains uncertain. Some geologists believe the continent sank entirely about 25 million years ago, later rising in places through tectonic uplift. Others argue that some regions remained dry throughout its history.
A reminder of Earth uncharted depths
The recognition of Zealandia as a continent has opened as many questions as it has answered. Why did it thin and sink so dramatically? How did its ecosystems evolve before submergence? And most intriguing of all could other hidden landmasses still lie beneath the world’s oceans?