Lough Dan () is a scenic boomerang-shaped ribbon lake largely set on private property, in the Wicklow Mountains in Ireland. Lough Dan lake lies at the base of Luggala and Knocknacloghoge mountains. The lough is fed by the Cloghoge (draining Lough Tay), and Inchavore rivers, and is drained by the River Avonmore. Part of Lough Dan forms part of the Guinness Estate at Luggala, and has limited public access.