The 16660 replaced the 1665 and doubled the Sea-Dweller's depth rating, from 610 metres to 1,220. It was the first Sea-Dweller with a sapphire crystal in place of the domed acrylic, carried an enlarged helium escape valve, and introduced the calibre 3035, which brought a quickset date to the line for the first time. Matte dials with painted markers came first; glossy dials with white gold surrounds appear on later production.
Reference record
Production
1978–1989
Model
Sea-Dweller 4000
Case material
Stainless Steel
Case size
40mm
Movement
Automatic
Calibre
Cal. 3035
Dial colours
Black
Market value band
$10k – $16k
Notable
—The calibre 3035 was the first Sea-Dweller movement with a quickset date.
—The helium escape valve at nine o'clock is larger than the one fitted to the 1665.
—Like every Sea-Dweller of its era, it has no cyclops magnifier over the date.
What the specification implies
—A flat sapphire crystal with no date magnifier is correct here; the domed acrylic belongs to the preceding 1665.
—The helium escape valve sits at nine o'clock on the case band.
Common questions
When was the Rolex 16660 produced?
The 16660 was produced from 1978 to 1989.
What movement does the Rolex 16660 use?
The Rolex 16660 runs the Cal. 3035, an automatic movement.
How do I check a Rolex 16660 with Watch Safe?
Look up the watch's serial number in the Watch Safe registry to see whether a record exists or a theft flag is attached. A registry search identifies records for a specific serial; it does not authenticate the watch. Authentication is performed in person by an independent expert authenticator, and Watch Safe records and publishes the result.