The Martin PBM Mariner is a twin-engine American patrol bomber flying boat of World War II and the early Cold War era. It was designed to complement the Consolidated PBY Catalina and PB2Y Coronado in service. A total of 1,366 PBMs were built, with the first example flying on February 18, 1939, and the type entering service in September 1940, with the last of the type being retired in 1964.

A maritime patrol aircraft (MPA), also known as a patrol aircraft, maritime reconnaissance aircraft, maritime surveillance aircraft, or by the older American term patrol bomber, is a fixed-wing aircraft designed to operate for long durations over water in maritime patrol roles — in particular anti-submarine warfare (ASW), anti-ship warfare (AShW), and search and rescue (SAR).