http://thewatchbox.com The 1999 IWC GST Deep One (ref 3527) is a landmark model and a grail to fans of dive watches. As the first dive watch to incorporate a depth gauge, it broke new ground and pushed the limits of what could be accomplished with purely mechanical technology. More than a case study in mechanical engineering, the Deep One is a tremendous collector's piece due to its rarity and links to a fading era of no-nonsense IWC tool watches. The complexity of the IWC caliber 8914 (based on Jaeger-LeCoultre's cal. 891) meant that production was curtailed after approximately 1,000 units had left the Schaffhausen factory. Moreover, the honest 43mm "tuna can" profile of the GST Deep One is an endearing look to long-time devotees of the International Watch Company. Its internal rotating dive bezel is a thoughtful safety measure and a tribute to IWC's heritage of dive watch innovations that recalls the original Aquatimer of 1967. IWC offers more than simple depth gauge; the system features a mechanical memory that records maximum depth for late reference. Even better, IWC includes a simple process for calibrating the instrument to the ambient surface pressure in order to read a correct "0" feet regardless of your location or weather conditions. The box set included with this IWC GST Deep One 3527 is one of the most comprehensive and entertaining we've every encountered. A full safety-test kit is provided in order to check the depth gauge for accuracy and proper function before each dive. An accessory textile strap is included for those who prefer to rock the "dive watch on a black strap" look as they take the plunge. For those who prefer to leave the watch on its factory bracelet, IWC equips the Deep One with a quick-change link replacement system that permits tool-free sizing of the bracelet. Each link features a spring tab that enables link-by-link sizing; the system is simple and maximizes user comfort. This IWC GST Deep One 3527 is available from thewatchbox.com in outstanding condition with full factory papers, technical manuals, boxes, and accessories. The condition of the satin-finished titanium reads as new and can be scrutinized in detail via high resolution images on www.thewatchbox.com. Video and content by Tim Mosso.