Why is usually that essential? If a unidirectional bezel is knocked and accidentally moved over a dive, it can only display a longer underwater time. Meaning the wearer will overestimate rather then undervalue immersion time, As well as in predicaments that call for decompression stops, This may be a make-it-or-break-it https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/