As part of the Republic of Ireland, Greencastle (Irish: An Caisleán Nua, meaning 'New Castle') is a commercial fishing port located in the northeast of the Inishowen Peninsula on the north coast of County Donegal in Ulster. The town takes its name from the ancient castle built in 1305 by Richard de Burgo, the Red Earl of Ulster, using distinctive green freestone. Also known as Northburgh Castle, it was built to guard the entrance to Lough Foyle. Greencastle has been welcoming mariners for centuries and is now a popular alternative disembarkation port for cruise ships visiting Derry. Due to the tidal nature of the Foyle Estuary, it is sometimes too shallow for cruise ships to reach Lisahally docks in Derry, and stopping at Greencastle also saves approximately 5 hours sailing round trip. The Inishowen Peninsula is Ireland's largest peninsula and was named number one in National Geographic Traveller's 'Cool List' for 2017 as part of County Donegal. The currency is the Euro (€) and there are ATM facilities in nearby Moville (2 miles). From Greencastle you can easily visit both the Republic of Ireland (Inishowen Peninsula) and Northern Ireland (Derry) in the same day.