The 60-minute graduated, unidirectional rotatable bezel of the Deepsea Challenge enables divers to precisely and safely monitor their dive and decompression times. It is equipped with a patented black Cerachrom bezel insert manufactured by Rolex in a virtually scratchproof ceramic whose colour is unaffected by ultraviolet rays. The graduation is coated via PVD (Physical Vapour Deposition) with a thin layer of platinum. The dial features large Chromalight hour markers and hands, filled with luminescent material that emits a long-lasting blue glow for excellent legibility in dark conditions.

The dial’s luminescent Chromalight display is an innovation that improved visibility in dark environments, an essential feature for divers. Hour markers in simple shapes – triangles, circles, rectangles – and broad hour and minute hands enable instant and reliable reading to prevent any risk of confusion underwater.

RLX titanium is a grade 5 titanium alloy selected by Rolex for its weightlessness and resistance to deformation and corrosion. Although insensitive to abyssal pressure, the experimental watch that accompanied James Cameron in the Mariana Trench still posed a wearability problem due to its weight, as it was made of 904L steel. The use of RLX titanium to create the case and bracelet of the Deepsea Challenge considerably lightened its weight: it is 30 per cent lighter than the experimental watch that inspired it. The watch also features a particularly visible grain in the satin finish on the bracelet and the case – with the exception of the crown guard. In order to highlight the curved profile of the lugs, the top edges have been chamfered and polished.