Swilly, Lough (lŏkh swĭlˈē) [key], inlet of the Atlantic Ocean, c.25 mi (40 km) long, Co. Donegal, NW Republic of Ireland. It is narrow and irregular in shape, with numerous islands. There is a lighthouse at Fanad Point. The resort town of Buncrana is on the eastern shore. On the lough, Wolfe Tone, an Irish revolutionary, was captured (1798) in an ill-fated insurrection against English rule.