Well, for my 1665th post, it was always quite inevitable that I would look at my favourite reference.
The birth of the Sea-Dweller was 1967. It marked the first release of a watch with a helium escape valve aimed specifically for professional divers. It was a true tool watch. The issue of helium was explained fully in the Rolex instruction manual that accompanied the Sea-Dweller of the era. To quote the instruction manual:
….”Man has built submarine houses and caissons in which the divers live in an artificial atmosphere made of gas mixtures, usually with a high percentage of helium. The very fine molecules of such gasses enter the watch but do not affect its operation. However, during decompression, there is a risk that the expanding gasses will cause the watch to explode. To avoid this by allowing the rapid escape of these gasses, Rolex have fitted a patent valve to their latest oyster model, the Sea-Dweller chronometer.”

The 1665 was born. It came with a calibre 1575 and was waterproof to a depth of 610m. The watch started production from 1967.
Of course, the precursor to the Sea-Dweller was a range of various prototype watches that were typically produced by Rolex for divers to test. These prototypes were not typically on sale. Indeed, the patent on the 1665 was not actually granted at the point when the prototypes were produced and so the patent pending was born.
Comex divers started to get 1665 watches issued from 1967. Interestingly, documentation that I have between Rolex and one of the test divers proves that Rolex used different diving companies as part of that testing. It was once thought that only Comex initially tested the prototypes. True, Comex were subsequently the diving company that aligned with Rolex, but initially there were a number of test diving groups.

Of course, as with Rolex, not everything is straight forward. The very first prototype, the so-called single red, was waterproof to only 500m. The first “Double Reds”, produced on a Mark 1 dial, had the familiar 610m depth rating. Much has been written about the various dial styles that have appeared on the 1665. In fact, each dial style deserves an entire post! One of the features that distinguishes the Mark 1 Patent Pending dial from the rest is the fact that the words “Sea-Dweller” and “Submariner 2000” are written in the same size font. Similarly, the “S” in “Sea-Dweller” is perfectly aligned with the “B” of “Submariner”. This can be seen from the close-up of this pair of Mk1 patent pending dials. One other quirk on the Mk1 is the tendency for the red writing to fade into pink. This can be seen on the left dial, but not on the right. It is believed that 100 Mk1 dials were made as prototype with about 25-35 surviving the prototype testing. These prototypes were typically given to divers to test. Some survived. Many did not. But they occasionally surface. The other superb quirk with this particular pair of patent pendings is that their serial numbers are sequential.

The Mk1 dial was followed by a Mk2 dial. This was also released as a prototype as the patent was still pending. With this dial, the font of the lower text, “Submariner 2000” was written smaller than the font on “Sea-Dweller”. Another difference is that if you look carefully, the D and W on Seadweller are so close together that they appear to kiss. Again, the Mk 2 patent pending was issued in very low numbers….purportedly just 99.

Of course, there are many variations on the 1665, and this is just a short sojourn into two of the earliest…almost pre-1665 prototypes. The nuances from version to version are many. Indeed, nuance extends from the quirky and very specific serial number range that Mk1 and Mk2 dials are found, to the bracelets and the casebacks.
Despite being such tanks, the reference has tremendous power. Indeed, when you catch one with a beautiful dial, there is little that rings a louder bell for me in Rolex. But it is power combined with control. The 1665 has a depth-on-the-wrist effect to it that is just incomparable with other Rolex. The superdomed nature of the plexi adds even more. But less talking…more showing. What do I mean?
Lets start with the superdome. Unmistakable!


