Founded in 1875 in New York by Joseph Bulova, the company quickly established itself as one of the leading names in American watchmaking, opening a manufacturing facility in Biel—a hub of Swiss craftsmanship—as early as 1912 to produce components of the highest quality. This diving watch features a Super-Compressor case, patented in 1956 by the Swiss company Ervin Piquerez S.A. (EPSA). This case design was used in several legendary models of the 1960s: the Lip Nautic-Ski, the Jaeger-LeCoultre Polaris and Deep Sea, the Longines Legend Diver, the Enicar Sherpa Super-Dive, and the Universal Genève Polerouter Sub. It is characterized by its two crowns (one for setting the time, one for operating the inner bezel) and its spring-mounted case back: as water pressure increases, it presses the case back against the gasket, thereby reinforcing the watch’s water resistance at depth. The watch was rated water-resistant to 666 feet, or approximately 203 meters, which was a remarkable achievement at the time. The dial is in very good condition, with a deep black finish. The luminescent hour markers are in good condition; note a slight chip on the triangular marker at 12 o’clock, visible in the photos. The markings on the bezel are silver and catch the light depending on the angle. The crowns are original and signed “Bulova.” The inner bezel adjustment mechanism is fully functional. The case back features an engraving of a diver’s helmet, the official EPSA (Ervin Piquerez S.A.) logo, the patent and model references, as well as the serial number. The movement is the very classic 25-jewel caliber (the number of jewels and the model are confirmed by the engravings visible in the photos). Frequency: 18,000 vibrations per hour. It is well-regulated with a deviation of less than 5 seconds per day. The designation “11AFAC” is decoded as follows: “11AF” is the mechanical base (Bulova’s 11AF family), the letter “a” indicates automatic winding, and “c” denotes the central seconds hand (sweep second). The movement’s frequency is 18,000 vph, and it contains 17 jewels. The “M3” marking is a production code indicating the year and quarter of manufacture. The letter indicates the year (m = 1963) and the number indicates the quarter. Due to the watch’s age, its water resistance can no longer be guaranteed: it is strongly advised against submerging this watch in water, as water ingress into the case could cause irreparable damage Founded in 1875 in New York by Joseph Bulova, the company quickly established itself as one of the leading names in American watchmaking, opening a manufacturing facility as early as 1912 in Biel/Bienne—a hub of Swiss horological expertise—to produce components of the highest standard. This dive watch features a Super Compressor case, patented in 1956 by the Swiss company Ervin Piquerez S.A. (EPSA). This case design was used in several legendary models of the 1960s: the Lip Nautic-Ski, Jaeger-LeCoultre Polaris and Deep Sea, Longines Legend Diver, Enicar Sherpa Super-Dive, and Universal Genève Polerouter Sub. It is characterized by its two crowns (one for setting the time, one for operating the inner bezel) and its spring-loaded caseback: the greater the water pressure, the more it presses the caseback against the gasket, actively reinforcing the watch’s water resistance at depth. Water resistance was rated at 666 feet—approximately 203 meters—a remarkable feat for the time. The dial is in very good condition, with a deep, rich black. The luminous hour markers are in good condition; note a minor loss of lume on the triangular marker at 12 o’clock, visible in the photographs. The bezel markings are silver-toned and catch the light depending on the viewing angle. The crowns are original, signed Bulova. The inner bezel adjustment operates perfectly. The caseback features an engraving of a diver’s helmet—the official logo of epsa (Ervin Piquerez s.a.)—along with patent references, model references, and the serial number. The movement is the highly regarded caliber with 25 jewels (the jewel count and model are confirmed by the engravings visible in the photographs). Frequency: 18,000 vibrations per hour. It is well regulated, with a rate deviation of less than 5 seconds per day. The designation "11AFAC" breaks down as follows: "11AF" is the base movement (Bulova’s 11AF family), the letter "a" denotes automatic winding, and "c" designates the center seconds (sweep second hand). The movement runs at 18,000 vph and comprises 17 jewels. The “M3” marking is a production code indicating the year and quarter of manufacture. The letter denotes the year (m = 1963) and the number denotes the quarter. Given the age of this watch, its water resistance can no longer be guaranteed. It is strongly advised not to submerge this watch, as water ingress into the case could cause irreparable damage.