She returned to New London and participated in local operations until November when a fleet exercise took her north of the Arctic Circle near Labrador.

In January 1948, designated a radar picket submarine, her hull classification symbol was changed from SS to SSR.

After conducting operations in the Caribbean during the first part of the year, she returned to her home yard, Portsmouth Naval Shipyard, in May for an overhaul which lasted until the end of October.

Spinax deployed to the Mediterranean Sea from 3 January to 3 March 1949, as the first postwar submarine unit of the Sixth Fleet.

The submarine operated with the Seventh Fleet and then visited the Philippines, Hong Kong, Formosa, and Japan before returning to San Diego on 7 May 1955.

All radar except search and fire control were removed, the communication facility was reduced to that of a regular submarine; and the combat information center was converted into living quarters.

Spinax departed San Diego on 3 May 1960 for a tour in the western Pacific with the Seventh Fleet which lasted until 3 November when she returned to her home port.