Just offshore from Alexandria Bay, Sunken Rock Light, on Bush Island, was constructed in 1847 to mark the entrance to the narrow passage where the shipping channel runs between Wellesley Island and the mainland..

In 1931, the characteristic of Sunken Rock Lighthouse was changed from fixed red to fixed green and in 1934 the light was electrified, increasing its intensity to 1,500 candlepower. It was converted to solar power in 1988 and today is maintained by the St. Lawrence Seaway Development Corporation pursuant to an agreement with the U.S. Coast Guard authorized under 14 USC 81.

From Alexandria Bay, the lighthouse can be viewed by going to the end of James Street and to observe it even closer, there are several boat tours that launch from Alexandria Bay.

(Photo of Sunken Rock Lighthouse, off of Alexandria Bay, taken from Boldt Castle. Courtesy of Susan Link.)