Loch Katrine is a loch in Stirling, Scotland. It is long about 13 km (8.1 miles) in the heart of Loch Lomond and The Trossachs National Park. There are bike hire facilities at the pier so the loch side can be seeked an be rewarded with stunning views. This loch has served as the principal fresh water supply for Glasgow city, for about 150 years. The principal access for the loch are either by Trossachs Pier, at the east side of the loch, or Stronachlachar , at the west side of it. There are a couple of small isles in the loch, such as Ellen's Isle, the Black Isle and Factor's Island.