It is 2 miles (3.2 kilometres) northeast of the town of Stromness, lies immediately to the south of the Loch of Harray and is close to the World Heritage neolithic sites of the Stones of Stenness and Ring of Brodgar.

[5] Its outflow is into the Bay of Ireland and the Hoy Sound at Brig o’ Waithe[6] where tidal currents influence the loch but cause little variation in its level.

[8] Its varying salt content supports a range of wildlife suited to marine, brackish and fresh water conditions[6] including burrowing worms, bivalves such as mussels and mya arenaria, the snail Hydrobia ulvae and various types of green algae known as charophytes.

[8] It provides a wintering ground for a wide variety of wildfowl including pochard, tufted duck, scaup and goldeneye.

The loch and its surrounding area underwent detailed geophysical and multibeam sonar surveys in 2011 and 2012 to investigate the drowned palaeo-landscape.