The Grail Watch Series: Sea-Dweller

There are a number of pieces in the Rolex stable that have earned the epithet ‘iconic’ over the years—timeless examples of design and engineering virtuosity that have lifted the brand far above the status of mere watchmakers.

Models such as the Submariner and the Daytona can easily lay claim to being in such exclusive company. Both are groundbreaking in their own ways, setting the benchmark for other manufacturers to follow.

However, within these groups of emblematic watches are a very specific subset that, for whatever reason—be it rarity, history or provenance—have been elevated even further into horology folklore. These are the ones sometimes known as the holy grail watches.

It can take the minutest of details, particularly with Rolex, to turn an otherwise familiar piece into one of these highly-coveted and extremely valuable objects of watch collector’s desires. A change in shape of the crown guard here, the switch from matte dial to glossy there; even as tiny a variance as a shift in text font or color can send prices soaring and enthusiasts drooling.

For the first in our series covering some of the grail watches from Rolex’s extensive back catalog, we’ll take a look at two vintage examples of the brand’s middle child of dive pieces—the Sea-Dweller.

The Double Red

The relationship between Rolex and the pioneers of underwater exploration goes back almost to the formation of the company itself. The Oyster had emerged in the 1920s, proving itself during Mercedes Gleitze’s English Channel swim as the first usable waterproof watch case. Decades of typically relentless Rolex innovations followed, culminating in the Submariner in 1953, the blueprint for just about every dive watch that has followed for the last half a century.

While the Sub’s impressive 100m of water resistance was more than enough to cope with the demands of the burgeoning recreational diving community in the 50s and 60s, the professionals needed a more heavy duty solution, designed to withstand even deeper descents and one that would address the strangely more difficult problem of the ascents back to the surface.

The Helium Escape Valve

French commercial diving specialists COMEX, sometimes known as the NASA of the sea, had been at the forefront of the industry for several years by the time they started their collaboration with Rolex. The Compagnie Maritime d’Expertises had been experimenting with different gas mixtures to combat the dangerous effects of breathing compressed air at depth. Below 30m, the high proportion of nitrogen present had a narcotic effect on their divers, and beyond 60m, the partial pressure of the oxygen in the mix became toxic, causing seizures and blackouts.

The answer turned out to be helium, an inert gas with no narcotic side effects and one that eliminated the chance of oxygen toxicity when mixed at the right ratios.

While these Trimix and Heliox blends protected the human element, the watches the COMEX crews were using didn’t fare as well. After a deep commercial operation, where divers might spend days or even weeks living in a pressurized underwater environment, they need to spend an extended period of time decompressing in a hyperbaric chamber, being slowly brought back to the surface pressure to allow the gas bubbles that had dissolved into their tissues to escape. Without taking the time to decompress, the bubbles expand too quickly in the falling pressure, causing the syndrome known as the bends.

It soon became clear that the diver’s bodies were more efficient at this off-gassing than their watches. Built up helium bubbles inside the cases increased rapidly, popping out the protective crystals and damaging the mechanisms.

The result of the COMEX/Rolex partnership created to come up with a resolution to the problem was the Helium Escape Valve (HEV). Initially retrofitted onto a ref. 5513 Submariner, the HEV was a small, one-way valve fitted in the 9 o’clock position on the Sub’s case that allowed the gases to release more quickly.

The Sub’s Big Brother

These hastily cobbled together prototypes, renamed the ref. 5514, were successful enough during the rigorous testing phase to lead Rolex, in 1967, to develop a watch purpose built for the job; the first of the commercially available Sea-Dwellers. Designed from the ground up with the HEV in place, the ref. 1665 was very similar to the Submariner, but with a thicker case and a new domed crystal which omitted the Cyclops lens over the date window.

On the dial, displaying with pride the uprated performance of their new diving flagship, Rolex included two lines of red text with the designation ‘Sea-Dweller, Submariner 2000’.

It is this lettering that earned the initial example the nickname the ‘Double Red Sea-Dweller’, or the DRSD for short.

It is a name that has become legendary among vintage watch collectors. In production for 10 years, the DRSD went through four different dial alternations, each one changed so slightly it takes a trained eye to tell them apart, but which put massive premiums on the price of the various models due to their comparative rarity.

Only 100 of the original Sea-Dwellers with the Mark I dial were ever built, making it the most valuable of the series. Additionally, and almost uniquely in the Rolex canon, the case backs are engraved. The first generation emerged before the patent for the new HEV had been granted, so along with the Rolex logo and the words ‘Gas Escape Valve’ and ‘Oyster’, these debut pieces also have ‘Patent Pending’ inscribed on the back, a detail that can reduce vintage collectors to delirium.

The models that followed all had their own idiosyncratic quirks. The follow up with the Mark II dial was granted its patent halfway through its production run, meaning there are some examples with ‘Patent Pending’ and some with “Rolex Patent’ etched on the back. A fault in the paint has caused some of these second run dials to fade from black to a rich chocolaty brown, giving them a desirability almost on a par with the original. There’s really no such thing as a mistake with vintage Rolexes!

The Mark III and IV dials vary only superficially in the placement of the text and the design of the brand coronet, and were produced in much higher numbers, making them the most accessible in the series, price-wise.

The Great White

By 1977, Rolex decided to do more to set the Sea-Dweller apart from the watch on which it was so clearly based, and dropped the Submariner tag from the dial text. Whereas the Sub had become their most universally adored creation, the vast majority of its fan base got no closer to the underwater realm than the pool bar. The Sea-Dweller was a different animal; over engineered and extremely capable, it was a watch meant only for serious professionals.

The first of this new wave, while it retained the same reference number of 1665, brought a number of alterations. Most significantly for collectors, gone was the red text. Instead, all of the lettering on the dial was in white, leading to its appropriately shark-based handle.

On the reverse too, Rolex introduced some variety to the Great White. The brand name now followed the curve of the case back rather than being engraved straight across as it had been on the DRSD. Both watches kept the same caliber, the Cal. 1575, recognized as one of the finest movements Rolex ever produced.

Although it was only in production for half as long as its predecessor, the Great White went through five different dial changes, distinguishable by such elements as the varying length of the lines of text or the size of the last letter R in ‘Chronometer’ (I’m not kidding!)

While the Great White enjoyed a successful run on a par with the DRSD, it was obvious its generation was coming to an end and the Sea-Dweller was overdue a major shake up. It even ran in conjunction with its eventual replacement for a number of years when the much altered ref. 16660, or the Triple Six, was launched in 1968. Featuring all that was bigger and better, such as a larger HEV and the first of the new high beat calibers, the Cal. 3035, the Triple Six Sea-Dweller also doubled the Great White’s water resistance, rated safe down to an incredible 4000ft.

Even so, the holy grail status of the last of the 1665 references was secure. Between it and the Double Red, they had cemented Rolex’s reputation as masters of the deep, a huge leap forward born of necessity, their technology on the cutting-edge and their design flawless.

Today, finding vintage examples of these historically important watches for sale isn’t difficult, although affording them can certainly present a challenge. Later models in good condition start well into five figures, while especially rare pieces such as the DRSD with the Mark I or II dial can easily top $100,000+.

But, as with all Rolexes, and particularly their grail watches, you would have to be very unlucky to lose money on a purchase. With the vintage market going from strength to strength, there are few better investments, and a classic Sea-Dweller reference from the brand’s golden age is one of the shrewdest.