His successor as captain, Marmaduke G. Bayne (later a Rear Admiral), remarked in an interview with the Naval Historical Foundation that "Bob McWethy was probably the best ship handler I have known. He was one with the ship." In 1948, while teaching navigation at the General Line School in Monterey, McWethy learned the Air Force was making weather flights to the North Pole. He was able to participate in the 103rd mission in B29 out of Fairbanks, AK. McWethy was interested to see that there were areas of open water in the Arctic, and realized that submarines would be able to surface if the conditions were right. “The idea of submarines operating beneath the ice soon became an obsession for McWethy,” wrote William R. Anderson in "The Ice Diaries: The Untold Story of the Cold War’s Most Daring Mission". “Russia was the new threat. The Arctic region was in Russia’s backyard, What better platform from which to stealthily operate and keep an eye on them than a submersible ship?" Working with his friend Waldo Lyon, McWethy was instrumental in drawing up the Pentagon's plans for navigation of the Arctic by nuclear submarine in 1957. As chief-of-staff for Submarine Squadron 10, wrote the orders that sent USS Nautilus on its secret crossing underneath the North Pole on August 3, 1958. In 1950 the Committee on Undersea Warfare of the National Research Council recommended study and development of underwater sensors to detect and track maritime traffic. Over the next decade, the Navy's Oceanographic Systems Atlantic command (OSL) began installing these SOSUS listening devices and monitoring them from NAVSEC facilities such as Ramey AFB, Grand Turk, Shelburne, and Nantucket. A primary task of SOSUS was to support anti-submarine warfare by detecting, classifying, and tracking submarine activity. McWethy was assigned to OSL in 1961. "It was an exciting time," he recalled in a speech in 2004. "The Soviets had just started sending nuclear submarines into the Atlantic." The new Charlie, Victor, and Yankee-class Soviet submarines were quieter and more difficult to detect. McWethy was appointed Commander Oceanographic System Atlantic (COSL) in June 1965 and commanded SOSUS operations in the Atlantic for three years His office expanded deployment of SOSUS in the Atlantic, especially in the GIUK gap, and opened NAVSEC stations in Keflavik and Argentia.