The Sea-Dweller is one of the major showcases among Rolex’s professional specialty watches. After decades of collaboration with professional divers, Rolex introduced this watch in 1967. Designed for professional deep-sea divers, the Sea-Dweller is water-resistant down to depths of 1,220 metres (4,000 feet) on the Sea-Dweller model. One vital feature that gives this watch is advanced waterproof capability is its helium escape valve, an invention patented by Rolex in 1967. For this model’s 50th anniversary, the latest Sea-Dweller watches now feature a 43 mm case, an increase from the original 40 mm case that came with previous models. New-generation Sea-Dwellers also include the innovative Calibre 3235 movement and the Cyclops lens over the date display.