The Martin P6M SeaMaster was an experimental strategic bomber flying boat built by the Glenn L. Martin Company for the United States Navy that almost entered service; production aircraft were built and Navy crews were undergoing operational training, with service entry expected in about six months, when the program was cancelled on 21 August 1959.

Envisioned as a strategic nuclear weapon delivery system for the Navy, the SeaMaster was eclipsed by the Polaris submarine-launched ballistic missile (SLBM).

Due to the political situation at the Pentagon and weapon system choices made amid budgetary constraints, the Navy promoted the P6M primarily as a high speed minelayer.

Its first attempt to address this came in the form of the USS United States, a large supercarrier intended to launch Navy strategic bombers.

In response, the Navy chose to create a "Seaplane Striking Force", useful for both nuclear and conventional warfare, including reconnaissance and minelaying.

The requirement issued in April 1951 was for a seaplane able to carry a 30,000 lb (14,000 kg) warload over a range of 1,500 mi (1,300 nmi; 2,400 km) from its aquatic base.

Originally the plane was to have a Curtiss-Wright turbo-ramjet engine,[2][3] but this ran into problems and a more conventional Allison J71-A-4 turbojet was employed, fitted in pairs in overwing pods to keep the spray out of the intakes.

[4] Eleven months later, on 9 November 1956, the second prototype, BuNo 138822, c/n XP-2, first flown on 18 May 1956, was also destroyed, due to a change made in the horizontal stabilizer control system without adequate evaluation before test flying the design.

These included rapid changes in directional trim, severe buffeting, and wing drop requiring high control inputs to counter.

Seaplane operations were a small component of U.S. naval aviation, and the P6M was significantly over budget and behind schedule and competing with aircraft carriers for funding.