Operation Pluto (Pipe-Lines Under The Ocean) was a Second World War operation by British scientists, oil companies and armed forces to construct undersea oil pipelines under the English Channel between England and France.

The scheme was developed by Arthur Hartley, chief engineer with the Anglo-Iranian Oil Company. Allied forces on the European continent required a tremendous amount of fuel. Pipelines were considered necessary to relieve dependence on oil tankers, which could be slowed by bad weather, were susceptible to German submarines, and were also needed in the Pacific War.

Geoffrey William Lloyd, the Minister for Petroleum, met Admiral Mountbatten, Chief of Combined Operations, whose area this was, in 1942 and then the Chairman of Anglo-Iranian. Hartley's idea of using adapted submarine telephone cable was adopted.