Eilean Donan is a small tidal island situated at the confluence of three sea lochs in the western Highlands of Scotland, about 1 kilometre from the village of Dornie. It is connected to the mainland by a footbridge that was installed early in the 20th century and is dominated by a picturesque castle that frequently appears in photographs, film and television. The island's original castle was built in the thirteenth century; it became a stronghold of the Clan Mackenzie and their allies, the Clan MacRae. In response to the Mackenzies' involvement in the Jacobite rebellions early in the 18th century, government ships destroyed the castle in 1719. The present-day castle is Lieutenant-Colonel John Macrae-Gilstrap's 20th-century reconstruction of the old castle.

A tidal island is a raised area of land within a waterbody, which is connected to the larger mainland by a natural isthmus or man-made causeway that is exposed at low tide and submerged at high tide, causing the land to switch between being a promontory/peninsula and an island depending on tidal conditions.