Lough Derg is the largest lake on the River Shannon. Its 13,000 hectares stretch 35 km from Portumna at its northern tip to Killaloe/Ballina at the most southerly point, and 12 km at its widest point, from Scarriff on the western shore to Youghal Bay on the eastern side. Geologically-speaking Lough Derg is a lake of two parts, each with very distinct characteristics. The northern half features headlands, islands and shoals of boulder-rich glacial drift surrounded by the natural beauty of r ...