This rare WWII Waltham U.S.A. Admiralty Pattern No.6 ASDIC Stopwatch is a historically significant naval instrument, issued to the British Royal Navy during the Second World War. Manufactured by Waltham Watch Company in the United States, this precision stopwatch was used in conjunction with ASDIC (an early form of sonar) to detect and track enemy submarines.

The robust design features a black dial with bold white Arabic numerals, split-seconds markings, and a centrally mounted second hand for precise timing. The case back is engraved with “Admiralty Pattern No.6”, confirming its official military designation. The stopwatch functions via a top-mounted crown and pusher system, with excellent mechanical response and smooth operation—testament to Waltham’s renowned watchmaking quality.

Its wartime use in sonar detection adds both technical interest and historical weight, making it a compelling artifact for collectors of WWII militaria, naval history, or vintage timepieces. Housed in its original metal casing (where available) and well-preserved, this stopwatch is a tangible link to the vital underwater warfare technology used by Allied forces.

An exceptionally rare piece, the Waltham Admiralty ASDIC stopwatch is both a fine example of wartime engineering and a valuable collector’s item.