Certina claims the DS-2 was extensively tested during the Tektite experiments, but all sources point to its predecessor, the much rarer SuperPH 500M (which was equipped with a locking bezel similar to that on IWC’s Ocean 2000 and GST Aquatimer), which was launched in 1969, a year before the DS-2. When the successor to the DS (the DS-2) was launched in 1968, two versions were available: one was waterproof down to 200m (reference 5801 303), the other waterproof down to 500m (reference 5801 123). The 38 mm version looks stunning on every wrist and shows off its exceptional quality and contemporary, compact design. The first diver’s models came on the market around 1960, shortly after the introduction of the DS product line (1959). “DS,” in case you are wondering, stands for the brand’s “double security” concept, and the main difference between the DS-2 and DS-3 is the number of crown-sealing techniques implemented. Despite having all the stuff that is needed to create a legendary watch, and despite having been issued as an official dive watch by the RAN (Royal Australian Navy), the Certina SuperPH 1000M does not appear to have been used as often as some of its rival models from that time (or, if it was, its usage has not been documented as well). The DS Action Diver has long been a favourite among admirers of the Certina collection. Regardless of all that, the DS-2 is definitely one of ’s all-time favorite vintage dive watches, mainly because it is one of the earliest “extreme” dive watches of that era, which challenged the way dive watches were supposed to look. 5801 302, later followed by the DS-3) its very distinctive look, but it’s also what made it rather difficult to wear, even by today’s standards (a good thing, from a collector’s point of view) and its massive caseback is not a great example of ergonomics, either. That bulky case is what gave the first Certina DS-2 SuperPH 1000M (Ref. A more modern interpretation of the original model, the reborn Certina DS-3 1000M (Ref.633.7128.42.61), featured an integrated helium release valve, a rather unusual hour hand (which made quite a few request for a modification, with an alternate set of hands) and most importantly, its 44-mm-wide, 14-mm-thick case was not quite as bulky as the original, at 18 mm thick. Back in 2004, Certina reintroduced one of its more unusual looking dive watches, launched in the early 1970s, as a limited edition.