Tasman Abyssal Plain

34°30′S 153°15′E / 34.500°S 153.250°E / -34.500; 153.250

The Tasman Abyssal Plain, or the Eastern Australian Abyss, is an abyssal plain located off the coast of southeast Australia in the Tasman Sea. Extending from southern Queensland to Tasmania, the large submarine plain is distinguished by its delicately sloping terrain and abundant marine biodiversity. The plain's deep sea floor is notable for its important sedimentary deposits and exceptional geological formations, whereby showcasing the earth's physical history. Also known as the East Australian Basin and Tasman Basin, it is characterized by an average depth between 4,000 m (13,000 ft) and 5,000 m (16,000 ft), with a diverse, though scarcely-explored, ecosystem.

A world-first observation of the largely-unexplored abyssal plain took place in 2017, where it created high quality seafloor mapping of Australia's continental edge from southern Queensland to Tasmania. The sonar observation revealed that the continental slope to the eastern Australian abyss was more convoluted and craggy than expected, with the edge being engraved by multiple canyons, sediment slumps, precipices and many areas of exposed rock. The majority of abyssal species discovered have extensive geographic and bathymetric distributions. Polychaetes, which are marine worms, were the leading members of the deep-sea macrobenthos, and therefore were valuable organisms for zoogeographical studies.