A loch and old mill dam, Greenan Loch lies in the centre of the Isle of Bute, 1¼ miles (2 km) west southwest of Rothesay. The Greenan Burn leaves the loch, flowing southwest. The loch provides a recreational coarse fishery stocked with carp, tench, bream and roach. Greenan Loch is also of interest for bird-watchers, with resident species including Mute Swan, Coot, Moorhen and Little Grebe and over-wintering wildfowl including Whooper Swan, Wigeon, Tufted Duck, Goldeneye, Teal, Mallard and occasional Pochard, Gadwall, Pintail and Scaup.
During World War II, a German plane returning from bombing Greenock jettisoned two bombs near Greenan Loch.
