THE ESSENTIALS

MAKE: ZENITH
MODEL: A3637
YEAR: 1970
BOX/PAPERS: NO/NO
CASE DIAMETER: 43mm
CASE MATERIAL: STAINLESS STEEL
BRACELET MATERIAL: STAINLESS STEEL
MOVEMENT: AUTOMATIC

In the late '60s, Zenith was at the cutting edge of modern sports watches. From their 3019-based automatic El Primeros, to keyhole-case dress watches like the A6620, and this—a 1000m dive watch—they were doing it all.

When the Sub Sea 1000m entered production, Zenith was already producing seven other dive watches, ranging from the 50m A3634 to the mighty Defy Diver A3648, which Zenith has recently re-released in a modernised guise. The Sub Sea 1000 we have here is certainly the most obscure. Four variations were produced—black, blue, yellow, and this, the only bi-color option: black and orange.

The case is interesting too. With a double-seal system, it had to be screwed down both from the caseback and from the top ring that secures the mineral glass—necessary for achieving the quoted depths at the time.

This example has remained in wonderful condition. The tritium lume plots have darkened but remain intact, as do the hands. The inner minute ring has a scratch between the 35 and 41 hashes. The bi-directional acrylic bezel has no cracks and works perfectly. The original Gay Frères rail-style bracelet, stamped 1/69, is in superb condition and can accommodate a 19.5cm wrist.

The watch was serviced last year and is still running well at +9 s/d, 250 amps, with a beat error of 0.2 ms.