Location of Inishowen Peninsula

There are several small outlying islands off the Inishowen coast, most notably Inishtrahull and Glashedy islands, both uninhabited, although the former was inhabited until the early twentieth century. Inch, located in Lough Swilly, is technically no longer an island, as it has a causeway connecting it to the mainland at Tooban, south of Fahan.

Lough Swilly is a fjord-like lough, and was of strategic importance for many years to the British Empire as a deep-water harbour. It is also famous as the departure point of the Flight of the Earls. Lough Foyle is important as the entrance to the river Foyle, and the city of Derry, but is much more shallow than Lough Swilly, and requires the use of a guide boat to guide ships to and from the port of Derry.

A large area of land, most of which now forms part of