Loch Katrine is a freshwater loch in the Trossachs area of the Scottish Highlands, east of Loch Lomond, within the historic county and registration county of Perthshire and the contemporary district of Stirling.
The loch is about 8 miles (13 km) long and 1 mile (1.6 km) wide at its widest point, and runs the length of Strath Gartney (Gaelic: Srath Ghartain). It is within the drainage basins of the River Teith and River Forth.
It is a popular scenic attraction for tourists and day-visitors from Glasgow and nearby towns; fly and boat fishing for trout are permitted on the loch from spring to autumn.
It also serves as a reservoir for the water supply of the Glasgow conurbation, some 30 miles (48 km) south, being connected by two aqueducts constructed in 1859.
