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ROLEX BLOG

Rolex Sea-Dweller 16660 “Triple Six” Ultimate Guide

October 6, 2021

BY Paul Altieri

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Affectionately known as the “Triple Six” among collectors due to its reference number, the Rolex Sea-Dweller 16660 is what we call a transitional reference. Rolex first introduced the Sea-Dweller ref. 16660 in 1978 as the second reference to join the saturation diving watch collection. It was the bridge between the vintage Sea-Dweller 1665 that came before it and the succeeding Sea-Dweller 16600, featuring design details from both generations. With that in mind, it’s important to note that Rolex produced both the Sea-Dweller 1665 and Sea-Dweller 16660 simultaneously for about five years.

The reference 16660 is a significant model in the Sea-Dweller’s history because it brought about some key changes to the watch, such as a new crystal material, a new movement, quickset date functionality, and double the water-resistance. The youngest Sea-Dweller 16660 is now over 30 years old, which means that the “Triple Six” is technically a vintage Rolex watch. However, at one point during the watch’s decade-long production run, Rolex updated the dial from matte to glossy with applied hour markers. Therefore, earlier examples of the Sea-Dweller 16660 appear more vintage in style than later versions. If you’re looking to add this classic Rolex tool watch to your collection or are just interested to learn more about it, dig into the details with our ultimate guide to the Rolex Sea-Dweller 16660.

Rolex Sea-Dweller Reference 16660

Rolex Sea-Dweller 16660 Triple Six Glossy Tritium Dial

Sea-Dweller 16660 Quick Specs

– Production Years: 1978 – 1989

– Case: Stainless steel, 40mm

– Bezel: Unidirectional, black aluminum insert, 0-60 minutes scale

– Dial: Black, matte with painted hour markers or glossy with applied white gold hour markers

– Lume: Tritium

– Functions: Hour, minute, seconds hand, quickset date

– Crystal: Sapphire (flat)

– Helium Escape Valve: Yes

– Water Resistance: 4,000 feet / 1,220 meters

– Movement: Rolex Caliber 3035 (automatic)

– Strap/Bracelet: Oyster bracelet, stainless steel

Click here for our Ultimate Buying Guide on the Rolex Sea-Dweller.

Rolex Sea-Dweller 16660 Triple Six Glossy Dial

The Design Improvements Of The Sea-Dweller 16660 “Triple Six”

The Sea-Dweller is a Rolex diving watch that was made specifically for saturation divers. As a result, all Sea-Dweller watches feature a waterproof Oyster case, a helium escape valve (HEV), a rotating timing bezel graduated to 60 minutes, and luminous hands and markers on the dial. The HEV serves to automatically release any trapped gasses in the watch that could have built up during prolonged exposure to a saturating diver’s highly pressurized environment. Expelling that gas from the watch reduces the risk of the crystal popping off (due to changes in pressure) during decompression periods.

Sea-Dweller 16660 Timeline:

– 1967: Rolex debuts the Sea-Dweller watch and launches the reference 1665.

– 1978: Rolex introduces Sea-Dweller ref. 16660.

– 1983: Rolex stops production of the Sea-Dweller ref. 1665.

– 1983/1984: Rolex replaces the matte dial of the Sea-Dweller 16660 with a glossy dial.

– 1989: Rolex stops production of the Sea-Dweller ref. 16660 and replaces it with reference 16600.

Like the preceding Sea-Dweller 1665, the reference 16660 sports a 40mm stainless steel case, a rotating black bezel, a stainless steel Oyster bracelet, and a black dial with a date window at 3 o’clock. However, the then-new reference also boasted several significant updates.

Rolex Triple Six Sea-Dweller 16660 Gloss Dial

Rolex Sea-Dweller 16660 Updates:

The Rolex ref. 16660 “Triple Six” was the first Sea-Dweller with a sapphire crystal protecting the dial, replacing the domed Plexiglas crystal found on the older ref. 1665. Of course, sapphire crystal is now standard across all Rolex watches and is especially prized for its scratch resistance. Like all versions of the Sea-Dweller (up until the most recent version released at Baselworld 2017) the sapphire crystal of the ref. 16660 does not include a Cyclops magnification lens above the date window. Since all other Rolex date models include the Cyclops lens, this is a design detail that sets the older Sea-Dweller watches apart from the rest and is appreciated by many.

Furthermore, the Sea-Dweller 16660 was equipped with a larger helium escape valve. The new crystal material and larger HEV, coupled with a slightly thicker case, allowed the Sea-Dweller 16660 to boost its water resistance. The “Triple Six” Sea-Dweller is water-resistant to 4,000 feet (1,220 meters), which is double the rating of its predecessor.

Also new to the Sea-Dweller 16660 was a unidirectional bezel instead of a bidirectional one – a much safer option for divers since overestimating immersion times is far better than underestimating them.

To recap, the Sea-Dweller 16660 included the following enhancements:

– Sapphire crystal instead of Plexiglas

– Larger helium escape valve

– Double the water resistance (4,000 feet instead of 2,000 feet)

– Unidirectional bezel instead of a bidirectional bezel

Vintage Rolex Sea-Dweller 16660 Triple Six Matte Dial

The Dial Evolution of the Sea-Dweller 16660

As with many vintage Rolex models, there are several dial variations of the Sea-Dweller ref. 16660. What they all have in common, regardless of production dates, is tritium lume, Mercedes-style hands, and a black background with white writing.

Matte Dials

The first batch of the Triple Six models (approximate serial numbers: about 5.9 million to about 8.5 million) featured a matte black dial without surrounds for the printed tritium hour markers. Additionally, among these matte black dials, there are two main versions: Mark I and Mark II.

– MK 1: Shorter Rolex coronet under 12 o’clock. The “f” in “ft” is above the letter “E” in “SUPERLATIVE.”

– MK 2: Longer Rolex coronet under 12 o’clock where sometimes the crown actually appears to touch the inverted triangle above it. The “f” in “ft” is above the letter “V” in “SUPERLATIVE.”

Glossy Dials with Applied Markers

Following the matte dials, Rolex outfitted the Sea-Dweller ref. 16660 with glossy black dials with white gold surrounds on the hour markers. The first batch of these glossy dials (Mark III) actually had two interesting details. The first one was that the hyphen between “SEA” and “DWELLER” was no longer included. The second was that these new glossy dials had a defect, which caused many examples to crack (known as “spider dials” among some vintage collectors).

Rolex remedied the situation and offered up a second version of the glossy dial (Mark IV) with no cracking problem and the return of the hyphen in Sea-Dweller name. The crown was also slightly elongated and the font slightly altered. It’s worth noting that some of the once glossy dials are turning matte as they get older. As expected, this is now something that has piqued the interest of vintage Rolex collectors worldwide.

– MK3: Glossy dials without a hyphen between “SEA” and “DWELLER.” Prone to cracking effect on the dial.

– MK4: Glossy dials with improved resistance to cracking and return of the hyphen in the “SEA-DWELLER” name.

COMEX Sea-Dweller Dials

From around 1980 to 1984, Rolex delivered Sea-Dweller ref. 16660 watches to COMEX (a French deep-sea engineering company), complete with the large COMEX logo on the dial. These COMEX versions are some of the rarest and most desirable versions of the Sea-Dweller ref. 16660. It’s reported that only 200 examples of the Sea-Dweller 16660 COMEX were produced.

The first batch of those watches featured the older matte style dial with two lines of writing (no Superlative Chronometer Officially Certified text). By some estimates, only 50 out of the 200 had matte dials while other estimates say it could be up to 100 examples. The remainder of the COMEX Sea-Dweller 16660 had glossy dials with white gold surrounds and four lines of text.

Rolex Sea-Dweller 16660 Triple Six Stainless Steel

The Movement Of The Rolex Sea-Dweller 16660

In addition to the above modifications, the Rolex Sea-Dweller ref. 16660 also had a new automatic movement ticking inside. The new model housed the Caliber 3035, which replaced the Caliber 1575 of the previous Sea-Dweller ref. 1665. The Caliber 3035 is automatic winding with 27 jewels and adjusted to 5 positions and temperature. It is also a COSC-certified chronometer movement, denoted by the “Superlative Chronometer Officially Certified” text on the dial of all Sea-Dweller 16660 watches.

The new Caliber 3035 operated at a higher frequency – 28,800 beats per hour rather than 19,800bph as before. Moreover, it was also more shock resistant, which is a much-appreciated feature for a robust dive watch intended for professional use. A super practical upgrade that the Caliber 3035 brought to the Sea-Dweller ref. 16665 was the quickset date feature. This meant that the date could now be set independently and without having to continuously turn the hands around the dial past midnight in order to get to the correct date.

How Much is the Rolex Sea-Dweller 16660 Worth?

The price of a Rolex Sea-Dweller 16660 depends on several factors such as dial type, age, and condition of the watch. However, you can expect the prices of vintage Sea-Dweller 16660 watches to start at around $12,000 for the newer glossy dial versions. Matte dial Sea-Dweller 16660 will cost more; it’s not uncommon to see a matte version selling for twice the price of a glossy dial version.

Since there are so few COMEX Sea-Dweller 16660 examples in the market, it’s hard to place an exact value on them. However, all COMEX dial Rolex watches will be incredibly expensive and this is especially true for the Sea-Dweller 16660. A few examples did sell at auction in 2020, ranging in price from $80,000 to over $100,000, and other examples have been known to trade hands for even more impressive values via private party sales.

Rolex Sea-Dweller Triple Six 16660 Glossy Dial

The Lasting Legacy of the Sea-Dweller 16660

The Sea-Dweller 16660 introduced many features that are still present in today’s versions. It was the first Sea-Dweller to have a sapphire crystal, a unidirectional bezel, a quickset date, and a water-resistance rating of 4,000 feet – all of which remain on the newest iterations of the Sea-Dweller that Rolex produces today.

For many collectors, the reference 16660 “Triple Six” represents the point in the Sea-Dweller’s history when Rolex’s ultra-professional saturation diver’s watch first started to take on what would ultimately become its modern form. This unique reference sits at the crossroads of vintage and contemporary, offering classic features like a 40mm case size and a matte dial (on early examples), paired with modern conveniences such as a scratch-resistant sapphire crystal and an Oyster bracelet with solid end-links.

For collectors and enthusiasts who appreciate the aesthetic and wrist presence of vintage Rolex watches, but who want something a bit more robust and worry-free for everyday wear and use, the Rolex Sea-Dweller “Triple Six” reference 16660 is the perfect watch that offers much of the historical intrigue and small variations, yet is more than tough to stand up to just about anything you find yourself doing, whether that is on land or deep below the surface of the ocean.

As such, the transitional “Triple Six” Sea-Dweller is a great vintage Rolex sports watch to have in any collection not only for its good looks but also because of the important role that it played in the evolution of the Sea-Dweller range. Furthermore, given the dial varieties available within the Sea-Dweller 16660 lineup, it’s a fun Rolex reference to study, hunt down, and collect.

Rolex Sea-Dweller Triple Six reference 16660

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2 Responses to “Rolex Sea-Dweller 16660 “Triple Six” Ultimate Guide”

  1. Matt says:

    Great history. Why is it called “triple 6” though?

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