In the year 1820, a Russian ship embarked on a journey that would forever alter our understanding of Earth's continents. While en route to serve up a unique dinner featuring penguins, the crew spotted an imposing wall of ice on the horizon.

This landmark sighting marked the official discovery of the Fimbul Ice Shelf, and subsequently, the unveiling of a new continent: Antarctica. This momentous event solidified the prevailing notion, widely embraced across English-speaking territories, that there exist seven major landmasses, comprising Europe, Asia, Africa, North America, South America, Australia, and Antarctica.

However, in a surprising twist of fate, the year 2017 witnessed a revelation that would challenge the conventional seven-continent model. Enter Zealandia, a long-forgotten landmass concealed to the southeast of Australia, now recognized as our planet's forgotten eighth continent. Scientists had long speculated about the existence of this hidden southern landmass, but it remained elusive for an astonishing 375 years, largely because it lay submerged beneath an impressive 1-2 kilometers (0.6-1.2 miles) of water.

Today, researchers are embarking on a quest to unravel the mysteries concealed within Zealandia's depths.
This month, an international consortium of scientists unveiled the most intricate maps of Zealandia to date, encompassing its sprawling five million square kilometers (two million square miles) of submerged terrain and its intricate geology. In doing so, they've begun to unearth clues regarding the formation of this enigmatic continent and the reasons behind its submersion beneath the waves for the past 25 million years.

Zealandia's origins trace back approximately 83 million years to the Late Cretaceous period. However, its story commenced nearly 100 million years prior when the mighty supercontinent of Gondwana, responsible for consolidating much of today's landmasses, began to break apart. During this disintegration, Zealandia separated from the surrounding land, eventually becoming Australia and Antarctica.

For a time, it might have existed as an island, but approximately 25 million years ago, it slipped beneath the ocean's surface.

The first substantial clues that Zealandia wasn't merely a fragment but a full-fledged continent emerged in 2002 when scientists employed bathymetry to examine the region's depths. It became evident that the ocean covering Zealandia was considerably shallower than the surrounding waters, suggesting a continental, rather than oceanic, tectonic plate underlay it. The conclusive breakthrough arrived in 2017 when various lines of evidence, including rock composition and thickness comparisons, confirmed Zealandia as a new continent—a remarkable discovery given that 95% of it remains submerged underwater.

Nonetheless, despite over a decade of intense exploration following the continent's identification, many aspects of Zealandia's early formation remained shrouded in mystery. This was partly due to the complex stretching and twisting that Zealandia underwent as it separated from Gondwana.

In 2019, scientists meticulously charted the geology of South Zealandia, revealing a history marked by stretching, tectonic forces, and the creation of oceanic crust. This complicated Zealandia's original form, making its history challenging to reconstruct. Rocks from Zealandia indicated that this stretching occurred in two phases, creating the Tasman Sea between Australia and New Zealand and, later, causing Zealandia to split from West Antarctica, giving rise to the Pacific Ocean.

However, many questions remained unanswered, particularly concerning the continent's unexplored northern half.

To further unravel Zealandia's secrets, another group of researchers focused on North Zealandia. They analyzed rocks dredged up from the Fairway Ridge, the northernmost tip of Zealandia, which had remained submerged for 25 million years. These rocks, a blend of volcanic and sedimentary types, provided valuable information about Zealandia's ancient past.

By examining their chemistry and radioactive isotopes, scientists estimated their ages and origins, uncovering a geological tapestry along Zealandia's length that aligned with West Antarctica's geology, corroborating their past connection.

In the next stage of their inquiry, scientists delved into magnetic anomalies in the ocean floor surrounding Zealandia. These anomalies offer a hidden record of tectonic plate movements over time, shedding light on the continent's ancient stretching, which persisted for millions of years and ultimately led to Zealandia's gradual sinking.

While Zealandia is now beginning to yield its long-held secrets, the vast majority of this enigmatic landmass remains concealed beneath kilometers of water, ensuring that uncovering its full story will be a journey filled with ongoing exploration and discovery.