Rinn Lough (Irish: Claonloch, also Irish: Loch na Reanna),[1] also known as Lough Rynn, is a freshwater lake in the northwest of Ireland.

It is located about 4 km (2 mi) south of Mohill.

[2][4] The water quality was reported to be satisfactory c. 2001 – c. 2006 maintaining a mesotrophic rating.

[5][6][n 1] but given a "bad ecological status" c. 2007 – c. 2009 due to pollution.

[6] The ecology of Rinn Lough, and Irish waterways, remains threatened by curly waterweed, zebra mussel, and freshwater clam invasive species.