Loch Ness was a famous lake in Scotland, home to the legendary Loch Ness Monster. (PROSE: Sting of the Zygons) It was located near Inverness in the Scottish Highlands, It was the greatest mass of fresh water in the British Isles and formed part of the Great Glen. The loch was 23 miles long, nearly 800 feet deep and covered over 700 square miles. (PROSE: The Secret Lives of Monsters) It was connected to other Lochs via underwater tunnels. (PROSE: Sting of the Zygons)
The Skarasen was released into it by the Zygons and was identified as the Monster, (TV: Terror of the Zygons) as was the Borad when he arrived in the Loch (TV: Timelash) before being killed by the Time Lords to prevent interference with the events of the Zygons and Skarasen. (PROSE: The Taking of Planet 5)
However, the Seventh Doctor once stated that Loch Ness had been home to a thousand different monsters since the world was formed, from the first primeval weed-monster to a near-mythical spiny-headed sea-serpent. (PROSE: Christmas on a Rational Planet)