With its impressive case diameter of 49 millimetres, the Aquatimer Perpetual Calendar Digital Date-Month turns heads both on land and underwater. The combination of 18-carat red gold with a blue dial and rubber-coated titanium gives the watch an appearance that is at the same time luxurious and sporty. In order to advance its large month display discs, the watch requires more power than the in-house automatic 89801-calibre movement can provide. When the date display advances at night, therefore, the quick-action switch taps a little of the energy, stores it, and then discharges it at the end of the month. The date and month discs have semi-transparent perforated covers that provide a view of the complex mechanism within. The rotor behind the see-through sapphire-glass back is distinctly functional-looking and likewise alludes to the reliability of research submarines. The exclusive flagship of the collection is limited to 50 watches and water-resistant to 10 bar.