It was carved by the Swan River, likely before the Tertiary, when this part of the continental shelf was above sea level.
[1] It occupies an area of 2,900 square kilometres (1,100 sq mi) and ranges in depth from 700 to 4,000 metres (2,300 to 13,100 ft).
The Perth Canyon is a feeding ground for pygmy blue whales, especially at the rims of the abyss.
It is also a training ground for the Royal Australian Navy Submarine Service, 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 200 kilometres (120 mi) in diameter and 1,000 metres (3,300 ft) deep.