X-1 (or SS X-1)[1] was a United States Navy Midget Submarine designed under project SCB 65.

X-1 served in a research capacity in rigorous and extensive tests to assist the Navy to evaluate its ability to defend harbors against very small submarines.

[3] Towed to Annapolis, Maryland, in December 1960, X-1 was reactivated and attached to Submarine Squadron 6 and based at the Small Craft Facility of the Severn River Command for experimental duties in Chesapeake Bay.

In tests conducted under the auspices of the Naval Research Laboratory, X-1 performed for scientists who observed her operations from a platform suspended beneath the Bay Bridge, to learn more about the properties and actions of sea water.

In 2001, X-1 was transferred to the Submarine Force Museum, in Groton, Connecticut, where she is on display before the main exhibit building.