The Rolex Explorer II Reference 1655 marked the debut of the Explorer II line when it was introduced in 1971. Designed as a specialized tool for cave explorers, the 1655 offered a solution for those in environments where distinguishing between day and night was impossible. Its standout feature was a bright orange 24-hour hand, which worked in tandem with a fixed steel bezel to allow the wearer to track both 12-hour and 24-hour time simultaneously.

The 1655 did not feature an independently adjustable 24-hour hand, meaning it functioned more as a day and night indicator than a true dual-time or GMT complication.

Housed in a 40mm stainless steel case, the watch was powered by the Caliber 1575 movement and included a date complication. Its distinctive dial design—featuring densely packed hash marks, unique numerals, and bold indices—set it apart from anything else in the Rolex lineup at the time.

During its production run from 1971 to 1985, the Explorer II Ref. 1655 was underappreciated and a slow seller. However, its tool-watch utility and unique 1970s design gradually gained the attention of Rolex collectors. What was once overlooked is now highly desired, and today the 1655 is regarded as a grail piece among vintage Rolex enthusiasts.

Despite being rooted in pure functionality, the 1655 carries a distinct period charm that has endeared it to collectors. As of today, the Explorer II Ref. 1655 typically trades between $25,000 and $45,000 on the secondary market, with prices increasing significantly for models in mint condition with the original box and papers.