Loch Awe is the third largest fresh water loch in Scotland with a surface area of 38.5 square kilometres (14.9 square miles). It is the longest fresh water loch in Scotland, measuring 35 kilometres from end to end with an average width of 1 kilometre.
The loch runs approximately south-west to north-east, roughly parallel to the two sea lochs of Loch Etive and Loch Fyne. Via the River Awe and Loch Etive it drains westward from its northern end and thus into the Atlantic Ocean.
Loch Awe is the site of two hydroelectric projects. One is a conventional turbine power station, with water extracted from the River Awe at a barrage, fed through underground pipes, and generating electricity as it flows into Loch Etive. The second is a more unusual pumped storage project, using a man-made loch in the hills above the loch; water is pumped up during times of surplus power, and used to power generators at times of peak demand. The second project, known as Cruachan from the name of the hill above, has a visitor centre, which includes tours into the heart of the mountain.
Loch Awe is renowned for its trout fishing. Salmon pass through the loch, coming past the barrage in the River Awe and continuing into the River Orchy. Loch Awe contains several ruined castles on islands, and at the northern end has one of the most photographed castles in Scotland, Kilchurn Castle, which in summer may be visited by a short boat trip or by a half mile walk from a small car park just after the bridge over the River Orchy. It was from Loch Awe and surrounding area that Clan Campbell established itself as a powerful family.