Donaghadee (Domhnach Daoi in Irish) is a town in County Down, Northern Ireland, situated on the east coast, about 18 miles from Belfast. The fishing port lies on the Ards Peninsula about five miles south east of Bangor.

Donaghadee is probably best known for its lighthouse and harbour, there's been a harbour at Donaghadee (or the 'Dee) since at least the 17th century.

Construction of the current harbour began in 1821, initially under John Rennie and completed by his son, also known as John Rennie. The harbour was designed to be deep enough for Steam Packets plying the 20-mile crossing of the Irish Sea to Portpatrick in south-west Scotland.

The harbour is constructed from limestone from the Moelfre quarries of Anglesey in north Wales, though the outer walls are the local graywacke blasted from a nearby quarry (where Copeland's Marina is now). The Moat in Donaghadee was built to house the explosives for this blasting. The harbour is made up of two independent piers.

[[1]] Picture of the Lighthouse (South Pier), Feb. 2004

Boats sail from the harbour to the Copeland Islands, most notably the M.V. 'The Brothers'.

Grace Neills, in the centre of Donaghadee, is according to the Guinness Book of Records, Ireland's oldest public house, opened in 1611 as the 'King's Arms'.

See also: List of towns in Northern Ireland