1969 Longines Ultra-Chron Diver 7970-1

The Longines Ultra-Chron Diver reference 7970-1 stands as a monumental achievement in horological history. First introduced in the late 1960s as a sporty, high-performance evolution of the Ultra-Chron line, it holds the distinction of being the world's very first high-frequency diving watch, and arguably the most accurate of its era.

"Ultra-Chron" stands for Ultra-Chronometer, a designation demonstrating that this mechanical masterpiece was built to be more accurate than a standard Chronometer. Longines famously guaranteed an accuracy of just one minute a month—a staggering two seconds a day. This exceptional precision allowed the Ultra-Chron to achieve a legendary milestone: it was the last mechanical watch in horological history to match the accuracy of the electronic tuning-fork movements of the era, but with the distinct advantage of requiring absolutely no battery.

Technically, the Ultra-Chron drew its inspiration directly from the Longines Observatory Chronometer, the Calibre 360. That historic caliber had previously set world records for accuracy (around 1/10 of a second per day) and represented the world’s first high-frequency wristwatch movement when it debuted in 1959. This reference leverages that unmatched heritage, backed by Longines' more than 100 years of experience developing high-beat movements for the official timing of sports events worldwide.

Design & Aesthetics

The 7970-1 flawlessly pairs serious underwater utility with bold, late-1960s industrial design. Its defining characteristic is the robust, tonneau-shaped cushion case water-resistant to 200 meters. To ensure vital readability even in murky waters, the stark black dial features a bright-red minute hand, while the index marks, handset, and the zero-marker triangle on the turning bezel were filled with highly visible tritium. Fitted with a practical calendar mechanism and a bidirectional rotating bezel to help divers easily determine their immersion time, the dial is beautifully signed with the applied, high-beat "Ultra-Chron" lightning-bolt logo above 6 o'clock.

This watch also comes with its original fitted box!

CONDITION:

Case: Sharp, unpolished condition with original factory brushing and crisp case geometry intact. Minor superficial hairlines & scratches consistent with age.

Dial & Hands: Flawless matte black dial. The signature red/orange minute hand remains incredibly vibrant. The hour hand displays some patina. Original tritium plots have aged to a beautiful, uniform creamy patina. Under UV, the tritium lume displays a uniform colour & consistent fade. 

Bezel: Original countdown/elapsed turning bezel insert is fully intact with crisp markings, showing light, honest vintage aging.

Movement: Caliber 431 high-beat automatic movement is fully operational, sweeping beautifully at 36,000 bph, and keeping excellent time. Date mechanism functioning correctly.  The movement was last serviced approximately 4 years ago. 

Bracelet: The watch is fitted with the original factory bracelet suitable for wrists up to 7.4in.  Note that non matching extension links have been fitted to allow the watch to be worn on wrists up to 8in. (Can be removed).

SPECIFICATIONS:

Year: Circa 1969

Case Material: Stainless Steel (Tonneau / Cushion shape)

Case Dimensions: 41 mm (excluding crown) | 44 mm lug-to-lug | 12.5 mm thickness Lug Width: 22 mm

Caliber: Longines In-House Cal. 431 (Automatic, 17 Jewels)

Frequency: 36,000 bph (Hi-Beat / 10 vibrations per second)

Accuracy Standard: Ultra-Chronometer Guaranteed (1 minute per month / ~2 seconds per day)

Complication: Time, Center Seconds, Date (at 4:30 position)

Original Depth Rating: 200 Meters (660 Feet). 

Accessories: Original fitted box in very good condition.