Lough Oughter  Lough Oughter () is a lake, or complex of lakes, in County Cavan covering more than . The complex of lakes lies on the River Erne, and forms the southern part of the Lough Erne complex. The lakes are bounded roughly by Belturbet in the north, Cavan town to the east, Crossdoney to the south and Killeshandra to the west. A 1977 report by "An Foras Forbartha" (precursor to the Environmental Protection Agency) describes Lough Oughter as the "best inland example of a flooded drumlin landscape" in Ireland, and details the varied biological communities of the area. According a National Parks and Wildlife Service summary of the site, there is nowhere else in the country with such "mixture of land and water occur over a comparable area", with many species of wetland plants, which are common to Lough Oughter, characterised as "infrequent elsewhere". The number of whooper swans which winter in the area represents about 3% of the total European population while the lake also houses the largest concentration of breeding Great Crested Grebes in the Republic, having become almost extinct in the 19th century. As an angling lake, Lough Oughter is designated as a suitable wetland for inclusion in the Ramsar List of Wetlands of International Importance. The Lough Oughter complex, along with Killykeen Forest Park, are designated Natura 2000 habitats, Special Areas for Conservation (SAC) and Special Protection Areas (SPA) under EU legislation. Lough Oughter is part of the UNESCO Marble Arch Caves Global Geopark. The main threats to the quality of the site, according to the National Parks and Wildlife Service, are water pollution sources like run-off from fertiliser and slurry applications, and sewage discharge which have raised the nutrient status of some lakes to hypertrophic. Afforestation has also resulted in some loss of wetland habitat and feeding grounds for some wintering birds. The Lough Oughter complex of lakes and wetlands is an ecotourism destination. Killykeen Forest Park, managed by Coillte, is a woodland of located five miles from Cavan town, and sitting alongside the Lough Oughter system. Trinity Island, located on Lough Oughter, was once home to a monastic settlement, and a friary on the island dates from the 12th or 13th century.