Hands-On: The Most Important (Rolex) Dive Watch

As a mere mortal, what are the odds of getting the chance to strap the most important diving tool watch ever produced by man onto ones own wrist? Watches of this magnitude are usually part of significant collections and typically hidden away from the public eye. That is the case with this piece as well but since it was yours truly who discovered its true nature back in early 2020, I was granted an audience with the king of the deep. The watch in question? A one-of-a-kind Rolex “Single Red” Sea-Dweller and the very first Sea-Dweller to ever feature the famous “Gas Escape Valve”, specifically made for one of the most daring enterprises in the history of diving.

Rolex “Single Red” Sea-Dweller Ref. 1665, case number 1820177, first valve prototype

Nowadays, the helium release valve is an integral feature of the Rolex Sea-Dweller but when the first 40 examples were produced in the second quarter of 1967, none was equipped with a valve. For a simple reason. At the time, Rolex was unaware of the issues posed by helium creeping into watches during prolonged exposure within dry hyperbaric chambers. It was not until the fourth quarter of 1967 that the idea for the valve reached the Genevean watchmaking company.

Patent drawings of Rolex’s first generation helium release valve (CH492246, filed on November 6, 1967)

Once patented, there was no immediate testing opportunity as SEALAB 3, the U.S. Navy project for which the first 40 Sea-Dwellers were made, was postponed from late 1967 to late 1968. In early 1968, however, the emerging French diving company Comex stunned the world with a groundbreaking hyperbaric dive named “Physalie” in cooperation with Dr. Ralph W. Brauer, director of the Wrightsville Marine Biomedical Laboratory of the University of North Carolina Wilmington. Together with Comex founder Henri Delauze, Brauer descended to a mind-boggling pressure equivalent to 1100 ft/335 m of depths. A leading hyperbaric researcher, Dr. Brauer was investigating the so-called “High-Pressure Nervous Syndrome”, a physiological barrier encountered at pressures of 1000 ft/300 m of depth preventing divers from reaching greater depths.

Dr. Ralph W. Brauer (left) and Henri Delauze inside the Comex hypebaric chamber in March 1968

Back then, Comex was working with the Swiss watchmaking company Omega in developing a special dive watch for saturation divers. Suddenly, Rolex saw themselves in a very tight spot as they had already lost the prestigious race to space against Omega. Comex was a dead end but luckily, the joint venture with the American university left a door open. Dr. Brauer had no obligation towards Omega. Subsequently, Rolex met with Brauer and learned a whole lot about his research and an upcoming offshore dive named “Hydra” which would involve, besides helium, also highly flammable hydrogen gas. Dr. Brauer was confident the new breathing gas mixture would alleviate the “High-Pressure Nervous Syndrome” and help reach unimaginable depths. In the future, Brauer told Rolex, more gases would be required to push beyond further physiological barriers in high pressure environments.

After their meeting, Rolex went back to the drawing board. Instead of trying to modify an already produced Sea-Dweller model, Rolex created a completely new case specifically designed for incorporating the valve.

First generation Rolex Oyster Gas Escape Valve

Since helium was no longer the only gas involved in saturation diving, Rolex used the broader term “Gas Escape Valve” to refer to the new device. If you ever wondered why it was called this way, it was based solely on Brauer’s work.

Oyster Gas Escape Valve engravings on the outside of Brauer’s watch (Photo: John Goldberger)

Another important detail of the caseback is the “Patent Pending” designation which was necessary as the patent application was still being processed. It is interesting to note that the engravings are punched rather than milled. They were executed in the same fashion as the engravings on pre Rolex Explorer watches given to members of the British climbing team that conquered Mount Everest in 1953.

Dr. Brauer died in fall 2000. With no immediate family, all of his possessions went to the University of North Carolina Wilmington where Brauer was a long tenured professor. While the university kept all of the scientific papers, science books and pieces of art, wordly items like his watch were auctioned off. This is how the watch entered the collector’s market.

Finally on my wrist!

According to Brauer’s assistant, the “Single Red” Sea-Dweller was found under the professor’s mattress, together with a stack of cash and a handgun. Incredible as this may sound, Dr. Brauer was a real life Indiana Jones with ties to the secret services and a true explorer always chasing the ultimate adventure.

For two decades, Brauer’s watch was “just” another “Single Red” Sea-Dwellers and despite having an absolutely puzzling later case number, nobody had the slightest idea what kind gem was hiding in full sight. It took my full commitment and months of holistic in-depth research in typical Perezcope fashion to ultimately figure out what this watch is all about.

So what is it like to wear this bad boy? Well, it is an awesome experience for sure. You can definitely feel the weight of history when you put it on but despite its historical importance and the monetary value that comes with it, the watch remains a tool watch in the truest sense. It feels sturdy, giving one the absolute confidence of a daily wear. Dr. Brauer rocked this watch on a regular basis and you can see it. Dial and hands have developed an incredible patina. See video below.

Dr. Brauer’s watch was specifically made for “Hydra”, an experimental Comex research program that would culminate in two depth records still standing today. The deepest offshore dive with 1752 ft/534 m (Hydra 8) and the deepest onshore hyperbaric descent to a mind-boggling pressure equivalent to 2300 ft/701 m of depth (Hydra 10), both achieved thanks to Brauer’s research.

Théo Mavrostomos at a pressure equal to 2300 ft/701 m

When I started Perezcope in late 2015, I could never have dreamed that one day I would be able to handle watches of this caliber. Everything is possible if you keep focussed and work hard.

“Hydra” vs. Japanese dragon (Tattoo: @micktattoozurich)

Brauer’s incredible piece of horological history is part of the collection of legendary watch dealer Tom Bolt aka @watchguru_. I would like to thank Tom for giving me this unique opportunity.

If you wish to go deeper down the rabbit hole of the early Sea-Dweller development, please read the following articles:

Read more: The Sea-Dweller Chronicles – Genesis of the decompressing watch
Read more: The Sea-Dweller Chronicles – Dry run and teaming up with Comex

Thank you for you interest.

History Of The Rolex Sea-Dweller

The Rolex Sea-Dweller was developed in the late 1960s for a new generation of divers. The following infographic shows the evolution of the watch in its historicall conetxt. Click the picture to zoom in.

This graphic is available as a high quality print in two sizes:

  • Regular small, 120cm x 68cm (47 x 26 inch): EUR 95.00 (plus shipping)
  • Regular, 150cm x 85cm (59 x 33 inch): EUR 135.00 (plus shipping)

Limited: 50 pieces, numbered and signed by Bob Barth, the legendary U.S. Navy Aquanaut who pioneered saturation diving during the famous SEALAB missions. Bob developed the idea for the Rolex Gas Escape Valve: Sold out

To order please contact me on Instagram: @perezcope , or send an email to: jose – perezcope – com.


  • As always, I appreciate your in-depth reporting and knowledge. Still hasn’t stopped me from owning a 233, but I do appreciate the actual value and history that it has associated with it (the movement, size, complications) even though the lineage is somewhat inconsistent.


  • Buonasera. Una domanda: possibile che siano stati fatti 2 quadranti diversi (la corona a ore 12 in modo evidente) per il “Single Red”?


      • Grazie mille, gentilissimo! In archivio avevo anche un altro quadrante (non ricordo dove ho trovato la foto) ma non ho mai approfondito la cosa.


  • Another brilliant write up & thanks for sharing the history of this iconic prototype SRSD.


  • Thank me? 🤔 it’s me that has to thank you for one of the greatest horological discoveries of the twenty first century x


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