IWC Schaffhausen GST Aquatimer watches

The IWC GST Aquatimer (IW3536) is the dive watch of IWC's GST sports line: a 42 mm case in steel or titanium with a rotating dive bezel. The GST name also covered a 39.7 mm Chronograph Automatic (IW3707), a 34 mm Chronograph MecaQuartz (IW3727) and a 43 mm Perpetual Calendar (IW3756), all built in the same two metals but without the diver's bezel. The steel Aquatimer 812AD is a different animal altogether, a 37.5 mm diver under an acrylic crystal.

The Aquatimers that carry no GST name are bigger watches. The Chrono-Automatic is a 42 mm chronograph diver in steel or titanium, with a 44 mm red gold version; the Split Minute Chronograph wears a 44 mm titanium case; the Aquatimer 2000 comes as a 42 mm titanium diver and as a 44 mm steel one; and the Deep Two measures 46 mm.

IWC revamped the entire Aquatimer collection for 2014. All the new models share the SafeDive bezel: a notched outer bezel linked through a sliding clutch to the inner timing ring, turning anticlockwise only, with the clutch housed in the bulge at 9 o'clock. Straps and bracelets come off at the press of a button. The 42 mm steel Aquatimer Automatic runs on an ETA 2892 and the 44 mm steel Chronograph on a Valjoux 7750, while the 46 mm titanium Automatic 2000 uses IWC's own calibre 80110 and is rated to 2,000 m. The 46 mm titanium Deep Three adds a mechanical depth gauge, with a blue hand for current depth and a red hand for the deepest point of the dive, both reading to 50 m. The 49 mm Perpetual Calendar Digital Date-Month pairs titanium with red gold and shows date and month in oversized digital windows.

The named editions mostly point to the sea. Blue with orange accents is the Cousteau colour scheme, the Galapagos Islands chronographs have rubber-coated steel cases, and the 44 mm Charles Darwin was IWC's first bronze watch. The Los Roques Automatic 2000, with blue lume, is limited to 50 pieces.