1978 Rolex Sea-Dweller "Great White" (Ref. 1665) Mk I Dial

In the early 1960s, deep-sea diving, particularly mixed gas diving, was advancing at a rapid rate. The Rolex Submariner was the quintessential diver at the time, born out of the late 1950s, which set the design standard for most dive watches that came after. The Rolex Sea-Dweller was first introduced in 1967 through the collaboration with COMEX, a French deep-sea diving company. Comex is sometimes referred to as the NASA of the deep seas and was the foremost pioneer in mixed gas saturation diving.

In typical Rolex fashion, form follows function. Most of the Sea-Dweller design was born out of the need to comply with the commercial ISO 6425 diving standard, which defines test standards and features for watches suitable for diving with underwater breathing apparatus in depths of 100 m (330 ft) or more. Rolex developed a rather simple and practical mechanism to solve this issue by developing a helium escape valve on the side of the case that allowed the helium particles to escape while still maintaining an ISO 6425 diving standard and water resistance rating.

The earliest prototype examples of the Rolex Sea-Dweller ref. 1665 featured a single line of red text, though the design was soon revised to include two red lines, giving rise to what collectors now commonly call the “Double Red Sea-Dweller.” In 1977, Rolex updated the dial once again, replacing the red text with a single, bold line of white “Sea-Dweller” text. This configuration became known as the “Great White.”

The Mk. I represents the earliest iteration of the Great White dial and retains a font profile closely resembling that of the Double Red Sea-Dwellers that preceded it. This subtle carryover gives the Mk. I a distinctly transitional character not found in the later dial variants.

The Sea-Dweller was undoubtedly the most advanced among the diving watches of its time, and the model remains at the forefront of advancement today.