Therasia is a piece of land.
Godrevy Lighthouse was built in 1858 -- 1859 on Godrevy Island in St Ives Bay , Cornwall .. Cornwall. Cornwall. St Ives Bay. St Ives Bay. Standing approximately 300 m off Godrevy Head , it marks the Stones reef , which has been a hazard to shipping for centuries .. Godrevy Head. Godrevy