USS M-1 (SS-47) was a unique submarine of the United States Navy. M-1 was designed as a test bed for the newest technology in submarine construction and design. As well as being the world's first double-hulled design (in contrast to Simon Lake's single-hulled concept), her battery was of a new design and was to have solved some of the past flaws. While no other M-class submarines were built, the lessons learned were incorporated into the following AA/T-class.