Loch Ruthven is a large loch which lies to the southeast of Loch Ness in the Highland region of Scotland. It is 2.25 miles long, extends over an area of 368 acres and is up to 42 ft deep. The most important breeding site in the UK for Slavonian Grebes, it has one of the highest populations of this species in Europe. These rare birds can also be found in several other local lochs. The RSPB has established a reserve at Loch Ruthven.
Loch Ruthven was designated a Ramsar site on August 31, 1992.