St Michael's Mount (Cornish: Karrek Loos yn Koos, (Carrek Los yn Cos), meaning "grey rock in the woods", also known colloquially by locals as simply the Mount) is a tidal island 366 m (400 yd) off the Mount's Bay coast of Cornwall, England, UK.
It is a civil parish and is united with the town of Marazion by a man-made causeway of granite setts, passable between mid-tide and low water.
Reference: Wikipedia