The Sea-Dweller, a professional tool watch for deep-sea diving from the Rolex stable, turns 50 this year and to mark this occasion the big crown has released an all-new model, with a larger case and modern caliber, at Baselworld 2017.

The new Sea-Dweller.The original Rolex Sea-Dweller, created in 1967, was born out of Rolex’s relationship with Comex, a professional French diving company. The initial models of the first ever reference (Ref. 1665) was developed from the Submariner and was almost exclusively supplied only to divers.

Among its many notable features was a helium escape valve, patented by Rolex that same year, which preserved the watch’s water-resistance while regulating the air pressure accumulated inside its case during the decompression phases of deep-water saturation dives.

A helium release valve for saturation diving is used here.

The new Sea-Dweller uses a 43 mm case, 3 mm more than the outgoing model. In the Rolex dive watch catalogue now, the Submariner has a 40 mm case, the Sea-Dweller gets a 43 and the Deep Sea gets a 45 mm case. For the first time, the model also gets a Cyclops lens over the date window at 3 for enhanced legibility.

In a move that will leave collectors happy, the text “Sea-Dweller” appears on the dial in red, just like in the original from 1967. Some models of the Ref. 1665 carried two red text lines on the watch dial (Sea-Dweller in the first and Submariner 2000 in the second) and came to be known as the Double Red Sea-Dweller. The Double Reds and Comex dial Sea-Dwellers are highly collectible vintage Rolex watches today.

The case of the 50th anniversary edition uses Rolex’s iconic Oyster construction. It has a middle piece crafted from a solid block of corrosion-resistant 904L steel; the fluted case back is hermetically screwed down with a special tool that allows only Rolex watchmakers to access the movement.

The screw-down crown, protected by a crown guard integrated into the case middle, uses Rolex’s Triplock triple waterproofness system, which ensures secure waterproofness for the watch’s interior in the same manner as a submarine’s hatch.

While the original was depth-rated to 2,000 meters, the new Sea-Dweller is water-resistant to a depth of 1,220 meters (4,000 feet). It features a 60-minute graduated, unidirectional, rotating divers’ bezel fitted with a patented black Cerachrom bezel insert.

The bezel’s graduations are PVD-coated with a thin layer of platinum. The black dial has large hour markers filled with Chromalight, a Rolex-developed luminescent material that emits a long-lasting blue glow in low-light conditions

The robust Cal. 3235The watch is equipped with the new Rolex Caliber 3235, a self-winding movement that boasts 14 patents. This represents the first time Rolex has employed this recently introduced, technically superior movement in one of its “Professional grade” timepiece.

Like all new Rolex watches, this Sea-Dweller carries the Superlative Chronometer certification, instituted by Rolex in 2015, which ensures a high level of precision and timekeeping performance (-2/+2 seconds per day).

A 4 Hz movement, it uses Rolex’s patented blue Parachrom hairspring, which Rolex says is up to 10 times more precise than a traditional hairspring when subjected to shocks, and has a power reserve of 70 hours.

The new Sea-Dweller’s solid-link Oyster bracelet, in 904L steel, is fitted with an Oysterlock safety clasp that prevents accidental opening. The bracelet also features a double-extension system that allows adjustments to be made without the use of tools, allowing the watch to be worn comfortably over a diving suit up to 7 mm thick.

Rolex’s Fliplock extension link extends the bracelet by 26 mm, while its Glidelock system allows fine adjustment of the bracelet length in 2-mm increments, for a total of approximately 20 mm.

The retail price of the Rolex Oyster Perpetual Sea-Dweller (Case ref. 12660, Bracelet ref. 97220) is $11,350.