Nomos Glashutte Watch Ahoi Datum 551. Sporty, robust, upbeat, modern, and with a great deal of aplomb: this watch is exceptional, visually and technically stunning. Despite its new coloring, the dial is reminiscent of the classic NOMOS watches Tangomat. But Ahoi is new, and more upbeat, sportier, and more modern that most other watches out there. With or without an extra large date indicator. The new model's aligned bezel, elegantly domed watch glass and flank guards make for the perfect figure (on the beach). The screwed down sapphire crystal back and crown ensures that everything stays tightly sealed, down to 20 bars, or 200 meters. This is because Ahoi is waterproof according to NOMOS' exacting test standards, which are not far off the DIN 8306 standard for diver's watches. A new waterproof watchstrap with NOMOS's own special winged clasp, a small red second hand and a dash of blue complete the watch. Superluminova makes Ahoi the perfect accompaniment, even in the dark. And what about the movement? Time is kept either by the NOMOS Epsilon caliber (without the date) or the Zeta (with date). Both are built in house by NOMOS and renowned for their accuracy and the performance of their mainsprings, thus ensuring the 40 mm diameter watch keeps setting reliably the pace.