This beautiful island-dotted lake lies about 16km (10 miles) east of Donegal Town. Legend has it that St. Patrick spent 40 days and 40 nights fasting in a cavern at this secluded spot, and since then it has been revered as a place of penance and pilgrimage. From June 1st to August 15th, thousands of Irish Catholics take turns coming to Lough Derg to do penance for 3 days at a time, remaining awake and eating nothing but tea and toast. It’s considered one of the most rigorous pilgrimages in all of Christendom.