Great Basses Reef Lighthouse, Offshore lighthouse on Maha Ravana reef, southeastern Sri Lanka.

Great Basses Reef Lighthouse is an offshore lighthouse on a reef 13 km off the coast of Yala National Park in southeastern Sri Lanka. It is a granite-based tower with an iron superstructure, designed to house a large hyperradiant Fresnel lens made by Chance Brothers. The light was first lit in March 1873 and is operated by the Sri Lanka Ports Authority.

A lighthouse was first proposed in 1856, but early work on an iron tower over a granite base produced no result. In 1867 a design by Alexander Gordon and James Nicholas Douglass was approved, with William Douglass as executive engineer. Two steam vessels carrying 120 tonnes of stone each laid blocks of 2 to 3 tons; the first stone went down in December 1870, the last in late 1872, and the light was lit in March 1873 at a cost of £63,000.

The reef's name in Sinhalese, Maha Ravana Kotuwa, means Fort of Great Ravana and links this location to Sri Lankan mythology. This connection to local legend gives the site cultural importance for people in the region.

Visiting requires a boat journey from Kirinda, taking about 90 minutes depending on sea conditions. Access is only possible during calm seas, so check weather and tide conditions before attempting the trip.

The reef below the tower is the site of the Great Basses wreck, an early 18th-century Indian ship carrying a cargo of silver rupees. Arthur C. Clarke and Mike Wilson discovered it in 1961, and the find later supported Clarke's interest in diving off Sri Lanka.