Peninnis Lighthouse is located on the outer headland at the most southerly point of the island of St Mary’s.
In 1716 a Ball of Fire, or Light, was proposed to be thrown in the air at intervals throughout the night by William Whiston. The plan was to make his navigation aid distinctive from that of St Agnes and other local lights, but this did not materialise.
Peninnis Lighthouse guides vessels entering St Mary’s Sound and Hugh Town harbour. It was built to replace St Agnes Lighthouse.
The lighthouse consists of a steel tower 45 feet high atop an open lattice tower. It was first lit in 1911.
It was built to be semi-watched, so did not need the service of a full-time lighthouse keeper. The third-order optic was driven by clockwork. The lighthouse was made fully automatic in 1922 with the introduction of acetylene gas and was one of the first gas-power lighthouses.
In 1992 the lighthouse was converted to electricity. In 2011 further modernisation took place and its range was reduced from 17 to 9 nautical miles. An LED lantern on the exterior of the gallery replaced the previous optic.
Peninnis Lighthouse can be easily accessed from Hugh Town and there is a coastal path around the headland. You can walk up to Buzza Hill, above Porthcressa Beach, where you will find a prehistoric entrance to a Bronze Age burial chamber.