The Explorer II watch is one of Rolex's most tool-oriented models. It features a steel case, a 24-hour engraved bezel, and a dial with two different hour hands. Rolex introduced the first Explorer II reference in 1971, specifically for cave explorers, to differentiate between day and night while spending extended periods in dark caves. The watch features an orange arrow-tipped hand that points to the fixed 24-hour bezel. Later, Rolex updated the Explorer II watch in the mid-1980s, adding independent hour hands and transforming it from an AM/PM indicator watch into a GMT watch. Besides, a white dial option was also introduced.

Both vintage and contemporary versions of the Explorer II with white dials are known as the Rolex Polar Explorer. The inaugural Explorer II ref. 1655 was only available with a black dial. However, all subsequent references (16550, 16570, and 216570) offer a choice of either a black or white dial. The Rolex Polar Explorer watch is one of the few Rolex sports watch collections with the option of a white dial. Due to this unique trait, it has always had a bit of a cult following among collectors.