Perth Canyon is a submarine canyon located on the edge of the continental shelf off the coast of Fremantle, Western Australia. it is approximately 22 kilometres west of Rottnest Island. It was carved by the Swan River probably before the Tertiary, when this part of the continental shelf was above sea level. It is about 1½ kilometres deep and 15 kilometres across, making it similar in dimension to the Grand Canyon.

It is a 2900 square kilometre area centred at 32 degrees south, 115 degrees east, and ranges in depth from 700 metres to 4000 metres. It drops from 200-metres within a few kilometres down to 1,000-metres and then it maintains as a deep gully all the way out to the 4,000-metre depth, which is about another 30-kilometres further west. It contains the world’s largest plunge pool – a depression in the canyon which is 2 kilometres long, 6 kilometres across, and 300 metres deep.

The Perth Canyon is a feeding ground for pygmy whales, especially at the rims of the abyss. It also happens to be a key training ground for the Australian Submarine Squadron, stationed at a naval base at nearby Garden Island.

In June 2006 the waters of the Perth Canyon hosted a 200km in diameter and 1000m deep ocean vortex. Visible from space, 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" by sucking in fish larvae.

References

• http://www.csiro.au/news/newsletters/0512_oceans/vod_main.jpg