"Tench"’s second period of active service lasted just over two decades. For the most part, she conducted routine training operations off the East Coast. Initially, she operated out of Norfolk as a unit of Submarine Squadron 6 (SubRon 6). While so assigned, she made her first deployment to the Mediterranean Sea in January 1952. Upon her return three months later, she resumed her schedule of east coast and Caribbean Sea operations. On the night of 13 January 1955, "Tench" accidentally grounded herself in ten feet of water 1,500 yards due east of the Cape Henry lighthouse, a Navy spokesman said. She got off the sand bar under her own power with the aid of high seas. She was stranded from 2100 hrs. to 2230 hrs. During the summer of 1955, the submarine changed homeports, leaving SubRon 6 behind for duty with SubRon 2, based at New London, Connecticut. In addition to periodic fleet exercises including Operation ICEX during the spring of 1960 in the Gulf of St. Lawrence, "Tench" served as a school ship for the Submarine School located at New London. That employment continued until October 1961 at which time she stood out of New London on her second deployment to the Sixth Fleet in the Mediterranean from which she returned early in 1962. Another extended period of duty with the Submarine School followed. That assignment was augmented by duty with various aviation and surface units in a series of antisubmarine warfare exercises. On June 8, 1965, "Tench" encountered the 13' 6" sailboat "Tinkerbelle" and its captain, Robert Manry as he made a historic trans-Atlantic voyage between Falmouth, MA and Falmouth, England. At the time, it was the smallest boat to cross the Atlantic nonstop. Early in April 1966, "Tench" broke that routine once again for a four-month cruise with the Sixth Fleet. This appears to have been her third and last tour of duty in the Mediterranean. Upon completion of the deployment, she returned once again to her New London-based training operations which occupied the submarine for the remainder of her active career.