Area · Co. Donegal
Lough Swilly is a long, narrow glacial fjord in County Donegal, stretching between the Inishowen and Fanad peninsulas. It connects the Atlantic Ocean to the River Swilly, with Buncrana, Rathmullan, and Letterkenny along its shores.
Lough Swilly sits between the western edge of the Inishowen Peninsula and the Fanad Peninsula in County Donegal. In Irish, it is Loch Súilí. The water is a glacial fjord, a long, narrow sea inlet. Only two others in Ireland share this origin: Carlingford Lough and Killary Harbour. The Atlantic meets the inlet at one end. The fresh water of the River Swilly fills the other. Towns like Buncrana on Inishowen and Rathmullan on the western side grew up where the water allowed.
The lough and the adjoining River Swilly (An tSúileach) share the same name. The local story points to Suileach, a legendary multi-eyed sea monster. Saint Colmcille reportedly killed it. Patrick Weston Joyce’s 1900 place-name history offers a different take. He suggests the name refers to whirlpools or eyes, with suileach meaning “abounding in eyes or whirlpools”. The water is known for its swirls, so the name fits the conditions.
Fanad Head and its lighthouse mark the northern entrance. Dunaff Head stands on the opposite side. In the south, islands like Burt, Inch, Coney, and Big Isle were poldered and reclaimed. The lough ends at Letterkenny. Driving along either shore is the best way to see it. You get the water, the headlands, and the small settlements. The light on the water in the late afternoon is distinct.
Plan a drive day. Choose the Inishowen shore or the Fanad shore, and let the road do the work. Boat trips run from Buncrana during the season. Check with current operators before travelling.
Where to stay
Stay on either shore — Buncrana or Letterkenny — and the lough is inside the day.
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Slieve League in southwest Donegal drops roughly 600 metres into the Atlantic, making it one of Europe's highest sea cliffs. The full scale is best experienced from the foot, reached via a two-hour walk from the Meenaleck car park.
Ardara is a small south-west Donegal town on the N56, named by The Irish Times in 2012 as the best village in which to live in Ireland. It serves as a practical base for the Bluestack Mountains and the west coast.
Buncrana is Donegal’s second-largest town, sitting on the Inishowen shore of Lough Swilly. It features the historic O’Doherty’s Keep and a rich textile heritage, serving as a practical base for exploring the peninsula.
Bundoran, County Donegal’s most southerly town, is a historic seaside resort named after the Doran River. It is a National Geographic top 20 surf town and the site where Mícheál Ó Cléirigh helped compile the Annals of the Four Masters.