Highliner Charters

25,000 Volts Under the Sea: Laying of the San Juan Cable (1952)

25,000 Volts Under the Sea tells the story of the laying of the world's longest single-length submarine high-voltage cable that delivered electric power from the Columbia River to the San Juan Islands in Washington State in 1951. The project, designed and carried out by the Bonneville Power Administration, involved laying four and a half miles of 25,000 volt electric transmission cable (conductor) across the Rosario Strait from Anacortes to Decatur Island, the installation of a wood pole line on the island, and then the installation of another two-mile submarine power cable to Lopez Island. The project cost $600,000 and was considered a major technological achievement at the time. This BPA film, also known as The Laying of the San Juan Cable, shows the planning, engineering, transportation and installation of the submarine cable. The cable, which was four and two-thirds inches in diameter and weighed 19 pounds per foot for a total of nearly three-quarter of million pounds, was wound for shipping in one continuous 7.5 mile length. The film also includes an animated model that demonstrates how the cable was carried inside the ship. The project began April 17, 1951 and Orcas Power and Light Cooperative began receiving power from BPA on July 22, 1951.

Cable failures in the 1960s led to a second cable installation in 1966 and a third in 1972.