Mark Island Light lies one nautical mile off Stonington, Maine at the western end of Deer Island Thorofare. Built in 1857 and first lit on New Year's Day, 1858, the square tower stands 25' tall. The keeper's house burned in 1959. Ownership was transferred in 1998 to Island Heritage Trust. Now a wildlife sanctuary with no landing facilities or buildings to visit, the light is best seen by boat trip or from the San Beach Road scenic turnout.