Part of a single-owner collection.

Introduced in 1967, the Rolex Sea-Dweller was developed as a professional diving instrument, designed to withstand the extreme conditions encountered by deep-sea divers. One of its most important innovations was the patented helium escape valve, allowing trapped gas to escape from the case during decompression and preventing the crystal from being forced off by internal pressure. Reference 1665 became an important chapter in Rolex's history of professional tool watches, offering water resistance to 610 metres.

Around 1977, Rolex introduced the version now affectionately known among collectors as the "Great White". Unlike its predecessor, the "Double Red Sea-Dweller", which featured two lines of red text, the new version displayed exclusively white lettering against its black dial. Several dial variations were produced throughout its production, with subtle differences in typography and text placement becoming important distinguishing features for collectors today.

The present example, dating to circa 1978, features an early "Mark I" dial, also referred to as the "Straight m Dial". This particular variation is distinguished by the upright, non-italic typography of the depth rating "2000 ft = 610 m", setting it apart from later dial executions. The dial also retains the period-correct "SWISS – T < 25" tritium designation at six o'clock.

With its distinctive case, domed acrylic crystal and matte black dial, reference 1665 represents an important period in the evolution of Rolex's professional diving watches.