The Isle of Portland lies in the English Channel, south of Wyke Regis, and west-southwest of London, at (50.55, −2.44). Portland is situated approximately halfway along the UNESCO Jurassic Coast World Heritage Site; the site includes of the Dorset and east Devon coast that is important for its geology and landforms. The South West Coast Path runs around the coast; it is the United Kingdom's longest national trail at . Portland is unusual as it is connected to the mainland at Abbotsbury by Chesil Beach, a tombolo which runs north-west to West Bay. Portland is sometimes defined incorrectly as a tombolo—in fact Portland is a tied island, and Chesil Beach is the tombolo (a spit joined to land at both ends).