Loch Druidibeag is a freshwater loch on South Uist in the Outer Hebrides, Scotland. Located near the island’s northern end, it is a Site of Special Scientific Interest and a Ramsar site, part of the South Uist Machair Special Area of Conservation and the South Uist Machair and Lochs Special Protection Area. Originally designated as a National Nature Reserve, it lost this status in 2012, and its previous biosphere reserve designation was withdrawn in 2013.