The Rolex Explorer II was presented by Rolex in 1971 as an addition to the 1954 model Explorer I. It features an additional 24-hour indication that can also be used as a second time-zone. This 24-hour indication, among other things, has been designed with regard to professional cavers, for whom a reliable temporal orientation independent of the outside world is of the utmost importance. Accordingly, at the design of the dial a special emphasis was put on excellent readability, even in the dark.
The initial Explorer II, Ref. 1655, was produced until 1984. It featured Cal. 1575GMT, like the similar Rolex GMT-Master, and a 39 mm case. The orange-tipped 24-hour hand is the signature feature; although later models had a red hand, these too faded to orange over time. This model is also sometimes called the “Freccione” (“Arrow” in Italian) or “Steve McQueen”, even though there is no evidence that the actor wore this model.
A transitional model Explorer II, Ref. 16550, was produced from 1985 through 1988. It is similar to the previous model but uses the new Cal. 3085 with an adjustable GMT hand from the Rolex GMT-Master II. The case is larger as well, at 40 mm.
The modern Explorer II, Ref. 16570, was introduced in 1989. It uses the new Cal. 3185, still with the adjustable GMT hand and fixed bezel. This was produced for over 20 years, upgraded to Cal. 3186 and the “ROLEX ROLEX” rehaut in 2007.
The latest Explorer II is Ref. 216570. Introduced in 2011, it uses Cal. 3187 and features a larger 42 mm case. The Explorer II Ref. 21670 is available with either a black or white dial, both in stainless steel with the Oyster bracelet.