Luna is a historic tugboat normally berthed in Boston Harbor, Massachusetts. Luna was designed in 1930 by John G. Alden and built by M.M. Davis and Bethlehem Steel. She is listed on the National Register of Historic Places and is a U.S. National Historic Landmark. In 1985, the Luna was designated as a Boston Landmark by the Boston Landmarks Commission.

Luna is the last surviving full-sized wooden ship-docking tug on the US Gulf and Atlantic coasts and was the world's first diesel-electric tugboat built for commercial service. These two distinctions have led to designation of Luna as a US National Historic Landmark. Today Luna is preserved at Chelsea, Massachusetts, in Boston Harbor, where her rehabilitation process has been underway since the tug was rescued from being broken up in 1995. Luna is the responsibility of the Luna Preservation Society and its progress is recorded in their website. Due to her wartime service with a civilian crew, Luna is also a member of the Naval Historic Vessel Association.

Luna was designed by John G. Alden (1884–1962), one of America's greatest and most prolific yacht designers, but was heavily influenced by the preferences of the tug's owner, the Mystic Steamship Company, and its subsidiary Boston Tow Boat Company. As a result, Luna's aesthetics embody the classical sweeping profile of the American harbor tug. The tugboat also had a very innovative propulsion plant: two diesel engines, each turning a generator and exciter to create DC current, which was then shunted (via prototypical switchboards) to a single DC motor (weighing 20 tons) attached to a single propeller shaft. The project was a showpiece for Thomas Edison's General Electric Corporation, which seized the challenge to design, build and deliver the components, in conjunction with their control subcontractors. Six years after Luna's delivery, GE reported that there were 33 diesel-electric tugs in service, 21 of which were GE installations.

Luna's wooden hull and deckhouses were built by the M.M. Davis Shipbuilding Company in Solomons, Maryland. The empty hull was towed from the Chesapeake to East Boston for outfitting at the Bethlehem Steel Shipyard in East Boston.

Upon completion, Luna was delivered to the Mystic Steamship Company of Boston as the first diesel-powered tug in their fleet. All the other tugs in the Mystic Steamship fleet - commercially known as the Boston Towboat Company - were powered by coal and oil-fired boilers and steam engines. The Mystic Steamship Company could trace its roots to the Boston Towboat Company, which had been founded by Boston's maritime executives to assure salvage, icebreaking, and ship towing services in 1857. The Mystic Steamship Company operated coal-carrying colliers and coal barges to transport coal from railroad piers in New York Harbor, Philadelphia, Baltimore and Newport News. This coal was used as a fuel, and as the basis to make lamp gas from coal and coke. Later, Boston Towboat was operated by Eastern Enterprises, owners of Boston Gas and various maritime operations, which is active to this day as Eastern Enterprises.

Luna and her sister, Venus, were the most powerful, reliable, and efficient boats in the Boston Towboat fleet and therefore were the first boats to be assigned every day. The majority of the tug's work involved docking and undocking ships in every part of greater Boston Harbor, from Salem's coal-fired powerplants and industries in the north, to Plymouth harbor in the south. Most of the time, the tugs were busy pushing and towing tankers, freighters, refrigerated cargo ships, passenger liners, warships, and large barges within Boston Harbor including Chelsea Creek, the Mystic River, the Charles River and Fort Point Channel. They occasionally operated on assignments as far away as Maine and New York.

During World War II, Luna was mobilized for service with the US Navy and US Army. She was used as a civilian-crewed and privately owned and managed tugboat at shipyards, repair yards, terminals, piers and anchorages from Bath, Maine to the Cape Cod Canal. Luna handled the many ships launched at the yards, guided damaged ships into drydock, took over the towing of damaged ships in the harbor from seagoing rescue tugs, undocked warships, transports and troopships bound for war, towed barges laden with ammunition, stores and fuel. She greeted returning warships and troop ships at the end of the war. Luna was the flagship of the Boston Towboat fleet until the end of the war, when modern surplus war-built tugs were sold off by the government. General Electric was so proud of Luna that its marine advertisements featured Luna into the early 1950s, a period that spanned almost two decades. During the 1930s, post war 1940s and early 1950s, Luna assisted the USS Constitution with her annual turnaround.

As more powerful diesel tugs and diesel-electric tugs were delivered to Boston Towboat, Luna was gradually relegated to back-up status and was retired in 1971. The tug was then used as an office and floating home, until it was acquired by a non-profit research institution in 1979. She was maintained on a shoestring budget by Captain Frances Rose Gage and many volunteers but sank twice in this period. The Luna Preservation Society took responsibility for her in 1995. Luna was declared a National Historic Landmark in 1989. Since being rescued from a graving dock in East Boston in early 1995, Luna has been rehabilitated for her role in Boston Harbor as an operating Landmark and educational vessel.