The Rolex Deepsea Ref. 136660 is a pinnacle of professional dive watch engineering, representing the ultimate fusion of Rolex’s deep-sea expertise with everyday wearability in a commanding 44mm Oystersteel case. This exceptional timepiece is engineered for the most extreme underwater environments, offering an astonishing 3,900 meters (12,800 feet) of water resistance, achieved through the patented Ringlock System and a helium escape valve at 9 o’clock, making it a true instrument for saturation divers. Its design is defined by the bold contrast of the jet-black dial, which provides a pristine canvas for the large, luminescent Chromalight hour markers and hands that emit a long-lasting blue glow for impeccable legibility in the darkest depths, while the unidirectional rotatable bezel features a virtually scratchproof black Cerachrom ceramic insert with platinum-coated numerals for precise dive timing. At its heart beats the advanced in-house automatic Caliber 3235, a Superlative Chronometer certified movement that delivers an impressive 70-hour power reserve, incorporates Rolex’s patented Chronergy escapement for superior efficiency, and features a paramagnetic blue Parachrom hairspring for exceptional shock and magnetic resistance. The watch is secured by the robust Oyster bracelet, crafted from high-corrosion-resistant Oystersteel and fitted with an Oysterlock safety clasp and the innovative Glidelock extension system, which allows for fine, tool-free adjustments of up to approximately 20mm, ensuring a perfect fit even over a diving suit. In its classic black dial configuration, the 136660 stands as a testament to Rolex’s relentless pursuit of mastering the abyss, offering discerning collectors the ultimate fusion of uncompromising technical capability and the refined, iconic design of the crown. Key specifications: 44mm Oystersteel case; black dial with Chromalight display; Caliber 3235 automatic movement; 70-hour power reserve; Oyster bracelet with Glidelock; 3,900m water resistance; black Cerachrom bezel; sapphire crystal.