The island is opposite Curry's Point on the mainland and is connected to the coast at low tide by a rocky causeway for about 16 hours a day.
[3] The main feature of the island is St Mary's Lighthouse which was built in 1898.
[4] In medieval times there was a chapel on the island dedicated to St Helen.
During the 19th century there was an inn, known as the 'Square and Compass', on the island, run by a Mr George Ewen.
In 1895, after complaints about rowdy customers trespassing on nearby land, the landlord, Lord Hastings, had Mr Ewen and his family evicted from the island.