On the northeast side of the park, the Passage Island Light guides ship traffic between the channel of Isle Royale's main island and Passage Island. Completed in 1882, the lighthouse originally used a Fourth Order oil-burning wick lamp and appeared as a fixed red light; later, it was modified to a flashing white light. Concession tours regularly travel to the island, giving visitors a glimpse of this now automated and unmanned sentinel of the past that continues to provide safe passage to ships today.
The most important of Isle Royale's light stations is Passage Island. Marking the narrow passage between Isle Royale's Blake Point and Passage Island, the light primarily guides Canadian ships traveling between Sault Saint Marie, Michigan, and Thunder Bay, Ontario, Canada. The ships traveling this route "set their course to thread the needle" in reference to this narrow passage which is only 3-1/4 miles wide.
As early as 1871 the U.S. Lighthouse Board requested an appropriation from Congress for the construction of the station. With the discovery of silver deposits on Lake Superior at Silver Islet, Ontario, north of Isle Royale, there was a sharp increase in shipping in the area. An appropriation of $18,000 was made by Congress in 1875 with the condition that the Dominion of Canada reciprocate by constructing a light on Colchester Reef, east of the mouth of the Detroit River, on Lake Erie. This condition delayed the plans to build Passage Island Light Station.
By 1880 the Dominion of Canada had made sufficient progress in the preparations for the Colchester Reef Light, so that actual construction could begin on Passage Island Light. The keystone was set in 1881 and the light was activated on July 1, 1882, three years before Colchester Reef. The station was originally equipped with a mechanical fog bell located in a small separate structure. The fog bell was replaced in 1884 by a 10" steam-powered fog whistle. When the station was established in 1882, a fixed red fourth order lens utilizing an oil burning wick lamp was used. On September 24, 1897, the original equipment was removed and replaced with a flashing white light. In 1912 a steel light tower, with electric light, was erected at Blake Point to help mark the narrow passage between Isle Royale and Passage Island. In 1913 the intensity of the light was increased to 50,000 candlepower when it was converted from an oil wick to an incandescent oil vapor utilizing a mantle. In 1928 the light was electrified. The station was manned as recently as 1957 and on December 20, 1978, it was fully automated.