Loch Rannoch is a freshwater loch in Perth and Kinross, Scotland. It is over 15 kilometres (9.3 mi) long in a west–east direction with an average width of about 1.2 kilometres (0.75 mi), and is deepest at its eastern end, reaching a depth of 130 metres (440 ft). The River Tummel begins at its eastern end, where the small village of Kinloch Rannoch can be found, whilst the wild expanse of Rannoch Moor extends to the west of the loch. The area surrounding Loch Rannoch, along with Rannoch Moor itself, was formerly part of the native Caledonian Forest that stretched across much of Northern Scotland. Native forest is now largely absent from much of the area, due partly to logging, and partly to the climate becoming wetter, and Loch Rannoch is now largely surrounded by commercial forestry and open hillsides, although a small area remains at the Black Wood of Rannoch on the southern shore of the loch.

The River Tummel is a river in Perth and Kinross, Scotland. Water from the Tummel is used in the Tummel hydro-electric power scheme, operated by SSE.