Perth Canyon
Perth Canyon is a submarine canyon located on the edge of the continental shelf off the coast of Perth, Western Australia, approximately 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 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 poola 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 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 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.