It lies about 30 km (19 mi) southwest of Westport near the village of Delphi.

[2] The lake runs in a narrow northwest to southeast direction, and is overlooked by the long ridge of Ben Lugmore 803-metre (2,635 ft), on its southwest shores, and by Barrclashcame 772-metre (2,533 ft) on its northeast shores.

Fin Lough in turn drains into Killary Harbour via the Bundorragha River.

[4] Fish species in Doo Lough include brown trout, sea trout, perch, salmon, Arctic char, three-spined stickleback and the critically endangered European eel.

[7] The northern end of Doo Lough is the site of a stone Celtic cross which was erected as a memorial to the 1849 Doolough Tragedy.