St Mary’s Lighthouse was built in 1898 on the site of an 11th-century chapel. The monks maintained a light on the tower.
The first-order optic was powered by paraffin. It was electrified in 1977, becoming the last Trinity House lighthouse powered by oil.
The optic was removed during the process and replaced by a sealed beam lamp array. The former optic put on display at the National Lighthouse Museum in Penzance. Following the museum’s closure, it was repatriated in 2011, and there are plans to move it back into the lighthouse.
St Mary’s Lighthouse was automated in 1982 and decommissioned two years later. Following decommissioning, its sealed beam array was transferred to the Inner Dowsing platform.
The island is accessible at low water via a causeway. Please check the tide times before crossing.