The Tasmanian Passage, also Tasmanian Gateway or Tasmanian Seaway, is the name of ocean waters between

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. It was formed from the separation of the two continental plates of Australia and Antarctica about 30 to 40 million years ago, and opened to water circulation around 33.5 Ma. The Tasman Passage connects the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

with the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

south of Australia. The term comes from geology. The distance between the two continents is currently about . Through the opening of the

Drake Passage The Drake Passage is the body of water between South America's Cape Horn, Chile, Argentina, and the South Shetland Islands of Antarctica. It connects the southwestern part of the Atlantic Ocean (Scotia Sea) with the southeastern part of the Pa ...

and the Tasmanian Passage, the Antarctic circumpolar current was able to form at the onset of the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, replacing the circumpacial equatorial flow conditions of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

. The emergence of the circumpolar current led to a thermal isolation of the

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

, since the exchange with equatorial warm waters was greatly reduced. As a result, the ice sheets of Antarctica formed and the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

entered the

Late Cenozoic Ice Age The Late Cenozoic Ice Age,National Academy of Sciences - The National Academies Press - Continental Glaciation through Geologic Times https://www.nap.edu/read/11798/chapter/8#80 or Antarctic Glaciation, began 34 million years ago at the Eocene� ...

(the current ice age).

References

Antarctic region Straits of Antarctica {{Antarctica-stub