There have been a number of lighthouses marking the entrance to Port St Mary and the Carrick Rock.
In 1812 the Inner Pier at Port St Mary was built with a 17-foot high lighthouse on the pier’s end.
The Inner Pier light later formed a transit with a fixed red light on a hill to the port’s western side.
The Inner Pier Lighthouse is now an octagonal white stone tower with a red band. The building also has a small window in the rear to be seen from within the harbour.
In 1882 a new breakwater, Alfred Pier enlarged the harbour, with a fixed green light at the end. In 1892 the pier was extended and a hexagonal cast-iron lighthouse built at its end.
The tower had been transferred from Port Erin and displayed a red occulting light every 10 seconds. When a vessel was due, a fog bell sounded. The bell was discontinued in the 1990s.
On 11th January 2009, a severe gale destroyed Alfred Pier Lighthouse, leaving only its stumps behind. The harbour authority quickly established a temporary light. However, it was not until November 2018 that a new tower replaced the temporary light.
The two lights form a transit to clear the Carrick Rock to the east. A black and red lattice tower marks the submerged rock.
Close to the inner harbour is a building which was used as an oil store for Chicken Rock Lighthouse.