Perth Canyon is a

submarine canyon A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km, from c ...

located on the edge of the continental shelf off the coast of

Perth, Western Australia Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth i ...

, approximately west of

Rottnest Island Rottnest Island ( nys, Wadjemup), often colloquially referred to as "Rotto", is a island off the coast of Western Australia, located west of Fremantle. A sandy, low-lying island formed on a base of aeolianite limestone, Rottnest is an A-class ...

. It was carved by the Swan River, probably before the

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

, when this part of the continental shelf was above sea level. It is an average of deep and across, making it similar in dimension to the Grand Canyon. It occupies an area of and ranges in depth from . Within a few kilometres its depth drops from down to , and then it continues as a deep gully all the way out to the depth, which is about another farther west. It contains the world's largest

plunge pool A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or shut-in. It is created by the erosional forces of cascading water on the rocks at formation's base where the water impacts.Mars ...

a depression in the canyon that is long, across, and deep. The canyon is considered "a perfect spot" for deep sea fishing. The Perth Canyon is a feeding ground for

pygmy blue whale The pygmy blue whale (''Balaenoptera musculus brevicauda'') is a subspecies of the blue whale (''Balaenoptera musculus'') found in the Indian Ocean and the southern Pacific Ocean. Reaching lengths of up to 24 metres (79 ft) it is small ...

s, especially at the rims of the abyss. It is also a training ground for the

Royal Australian Navy Submarine Service The Royal Australian Navy Submarine Service is the submarine element of the Royal Australian Navy. The service currently forms the Navy's Submarine Force Element Group (FEG) and consists of six ''Collins'' class submarines. The Royal Australia ...

, stationed at a naval base at nearby Garden Island. In June 2006 the waters around the Perth Canyon were the site of an ocean

vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in ...

in diameter and deep. It was visible from space, and scientists claimed at the time that it had the potential to affect the local climate and the climate further abroad. The vortex was described by scientists as a marine "death trap", as it sucked in fish larvae.

References

Landforms of Western Australia Submarine canyons of the Indian Ocean {{WesternAustralia-geo-stub

See also

References