The ‘Single Red’ Sea-Dweller, reference 1665, was the watch that started the lineage of one Rolex’s most important
professional tool watches. The very first ‘Dweller' was a prototype that was issued to professional divers to test
in the field. The most interesting aspect of these watches was that they were not equipped with gas escape
Rolex were experimenting with watches that could operate at much greater depths and so the prototype 1665 was depth
rated to 500m/1650 ft. Recent research has suggested that there were ten of these watches made. Of the ten, seven
were given to the underwater explorers who took part in the first Tektite project.
Tektite was an innovative experiment to build an underwater habitat in which the first aquanauts would live; which
they did for 58 days — a record at the time and the perfect extreme test for the prototype Sea-Dweller.
Rolex worked with a number of organizations and agencies in the development of the Sea-Dweller. Divers had been using
Rolex Submariners and the new prototype Single Red Sea-Dweller for professional diving work and specifically
saturation diving, where the divers were able to work at significant depths as they were breathing Heliox: a mixture
of helium and oxygen.
The problem was that the helium particles were small enough to seep into the seals of the watch and the watches were
known to ‘pop’ their crystals as the divers decompressed and the gases tried to escape from their watches at a
faster rate than they’d entered.
The helium escape valve was developed to combat this. It is essentially a one-way valve that allows the helium gases
to escape safely from the watch. It worked and is still a key feature of Sea-Dwellers today.
It’s a question that a lot of people wrestle with — to Sub or ‘Dweller. In reality, for all but the commercial
divers, a Submariner is more than adequate for most needs. The modern sapphire Sub is depth rated to 300 meters or
1000 feet. It is, in fact, over engineered. So who, other than professional saturation divers, really needs a watch
that can be used at depths of 1220 meters or 4000 feet? Well, nobody actually but it's very cool to know that it
At Baselworld 2008, Rolex unveiled the ultimate Sea-Dweller to date — the Deepsea, reference 116660 — a beast of a
watch. Depth rated to a remarkable 3900 meters (12800 ft), it is a watch that literally knows no limits — well that
is, up to 3900 meters.
Most people don’t even realize that the seas don’t even go that deep! To test the watches at this significant depth
some ground breaking machinery had to be designed and built. Rolex turned to long term partners Comex for this, who
developed the necessary testing equipment that can simulate the massive pressure that the watches would be subjected
to at their limits.
Rolex’s founder, Hans Wilsdorf launched the world’s first waterproof wristwatch in 1926: The Oyster watch. The Oyster
case succeeded in water sealing the three traditionally ‘leaky’ areas of a watch — the winding crown, the crystal
and the caseback.
The caseback of the Oyster case screws tightly against the mid-case of the watch, which is given extra protection by
a rubber gasket seal. Similarly, the winding crown screws down tightly onto a tube attached to the mid-case.
Finally, the crystal is pressure fitted onto the case using a crystal retaining ring or bezel. It is this simple, yet
perfectly engineered solution that has made all Rolex Oyster watches, and particularly the Sea-Dweller, the
world-dominating force in water-resistant sports watches.
All Sea-Dwellers feature a date function, even on the prototype Single Red. Equally, no Sea-Dweller has ever featured
a cyclops on the crystal. Rolex introduced the cyclops date magnifier in 1954 on the GMT Master, reference 6542 and
on the Datejust line. It didn’t appear on a diving watch until around 1966 with the introduction of the Submariner
date, reference 1680.
Of course, it would have been impossible for Rolex to have applied a date bubble onto the domed plexi crystal of the
1665 and not give the wearer a distorted view of the date aperture. With the introduction of a flat sapphire glass
on the reference 16660, applying a date magnifier would have been possible but Rolex never did. Possibly because it
could get knocked more easily when in use and therefore be a potential weakness or maybe they didn’t for purely
But now, on the occasion of the 50th anniversary of the Sea-Dweller, Rolex has finally put on the date bubble in this
year’s Basel darling, the Sea-Dweller, reference 126600. This is now the result of both time and technology aligning
to allow for the mounting of the cyclops and have it maintain its integrity all the way to its promised depth of
1200 meters (4000 feet).
In 2012 James Cameron, filmmaker and explorer, piloted the Deepsea Challenger submersible craft down to the deepest
known part of the Earth’s ocean, the Mariana Trench. He became only the third person to ever visit its depths and
the only person ever to accomplish it on a solo mission.
Rolex were partners in the mission and as a key part of their research and development they created another prototype
Sea-Dweller – the Deepsea Challenge. Never commercially available, the behemoth watch measured a colossal 51.5mm
across, 28.5mm deep and was depth rated to 12000 meters (39,370 feet)! The watch was attached to a manipulator arm,
during the entirety of the dive mission, and functioned well at a mind-boggling depth of 10898 meters.
The Sea-Dweller is undoubtedly a very good looking divers watch. Similar, aesthetically, to the Submariner, the
Sea-Dweller has a very passionate following amongst collectors who seek out rare variations. This has had a big
impact on the market and now prices for Double Red Sea-Dweller are very high.
Comex issued Sea-Dwellers will always be sought after, especially when accompanied by the diver’s dive logs and other
Comex associated paraphernalia. The two factory specification 1665s that are the main grails for ‘Dweller collectors
are the Single Red and the Mk1 Patent Pending Double Red Sea-Dweller (Mk1PPDRSD).
The Patent Pending was the very earliest version that was sent out to retailers and had ‘Patent Pending’ as part of
the caseback engraving text. Additionally, these watches are characterized by their two lines of red writing
typically having faded to a very pale pink.
The Sea-Dweller has always had to be engineered to be as pressure resistant as possible. The pressure at the
Deepsea’s limits of nearly 4km would be around 411 kg force per square centimetre. To enable the watch to withstand
such tremendous force, Rolex developed a new case assembly that they named the Ringlock System.
Essentially, it is a high resistance ring that sits within the mid-case onto which an extra thick sapphire crystal
sits on the top and a titanium caseback screws against at the back. Even back at the beginning of the family tree,
the 1665 had an extra deep crystal, the Tropic 39, that allowed for the thick bezel assembly and the extra pressure
that the watch would be subjected to at its limit.
One of the most desirable special order Sea-Dwellers is the so-called Omani 1665. These watches were ordered by
Asprey in London for presentation by Sultan Qaboos bin Sa’id. He presented these watches to members of the British
SAS who had served to defend his regime during the rebellion between 1970-1976. The watches are identifiable by the
presence of the red Omani Khanjar on the bottom half of the dial, replacing the four lines of text normally seen on
the Sea-Dweller. It is estimated that approximately 90 examples were made. Additionally, there are four known
examples with the Khanjar logo in gold…now find one if you can!