island in Carmarthen Bay of the Bristol Channel, Pembrokeshire (Sir Benfro) county, Wales. It lies 2.3 miles (3.7 km) south of the port of Tenby. The island is 1.5 miles (2.4 km) long and 1 mile (1.6 km) across at its widest. From at least the 6th century, when it was inhabited by Celtic monks, Caldey has been associated with religious communities. In 1906 it was bought by Anglican Benedictines, who built the present monastery and abbey, but since 1928 they have been succeeded by Trappists (Trappist) from Belgium, who farm the island and make perfumes and toiletries from herbs they grow. Its sister island, St. Margaret's, is a seal and bird sanctuary, and both islands are popular with tourists and naturalists. Caldey contains a small village and a lighthouse. Pop. (2001) 45.