Massachusetts Memorial Committee, Inc., Battleship Cove was incorporated as a nonprofit educational organization and granted §501(c)(3) status by the Internal Revenue Service in 1964.

Led by veterans who had served aboard Massachusetts during World War II, the group was responsible for the U.S. Navy's donation of the decommissioned vessel and its subsequent public display.

Soon after, the battleship was recognized as the official memorial to Massachusetts citizens who gave their lives in World War II and her interior spaces were reconfigured to accommodate exhibits.

The following year, USS Joseph P. Kennedy Jr., a Gearing-class destroyer, was added to the fleet and immediately designated as the Commonwealth’s official memorial to the Korean and Vietnam Wars.

Subsequently, both Joseph P. Kennedy Jr. and PT-617 received NHL status, giving Battleship Cove the highest concentration of such south of Boston.

The success of the overnight program, high visitation from school groups, and general admissions supported an expanded staff and improved ship maintenance efforts.

Massachusetts received eleven battle stars for World War II service and earned a reputation as a "Work Horse of the Fleet".

In the spring of 2000, Joseph P. Kennedy Jr. was brought to Rhode Island Sound for the movie Thirteen Days, portraying both herself and USS John R. Pierce.

On 2 June she started her second war patrol, and on 10 July fired torpedoes at a surfaced Japanese submarine, after which Lionfish's crew heard explosions and observed smoke through their periscope.

She subsequently fired on two more Japanese submarines and ended her second and last war patrol performing lifeguard duty (the rescue of downed fliers) off the coast of Japan.

In 1971, she was stricken from the Navy Register, and in 1973, she was unveiled for permanent display as a memorial at Battleship Cove, where she has evolved into one of the museum’s most popular exhibits and a monument to all submariners.

Originally commissioned by the East German Navy as Rudolf Egelhofer, Hiddensee was a Tarantul-class corvette built at the Petrovsky Shipyard in 1984, located near the former Soviet (now Russian) city of Leningrad (now St. Petersburg).

After 50 underway deployments in the Chesapeake Bay and Virginia Capes areas, Navy budget cutbacks severely curtailed operations, but she continued on as a research vessel until April 1996.

In 1946 she participated in the Operation Crossroads nuclear weapons tests in the Marshall Islands, followed by a short tour of duty in the Far East in 1947, after which she was placed out of commission in reserve at the Puget Sound Navy Yard.