f the Rolex Submariner was the original sports watch, then the Explorer II was the original extreme sports watch. Introduced in 1971 as a timepiece for cave and polar exploration, this was a watch with a very narrow target market. Though it was never a big seller for Rolex, the Explorer II remains a favorite of ours thanks to its purpose-built design, intended use and legendary Rolex build quality. Along with the equally capable Sea Dweller, it’s also the only Rolex sports watch to have not been rendered in a precious metal. And remember those great Rolex ads in National Geographic, depicting vulcanologists and spelunkers descending into inhospitable places? This was that watch. Singular in purpose and entirely uncompromising, the Explorer II was a pure tool.

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While the original Rolex Explorer had a bulletproof back story — the summiting of Everest — by the 1970s, it remained a small, quaint watch, belonging to an earlier era and devoid of complications or even crown guards. So Rolex created its bigger, badder descendant. The Explorer II was housed in a burlier 39mm case and featured the same protective crown guards as the Submariner. It also sported a fixed, engraved 24-hour marked bezel and an extra hand on the dial. That oversized blaze orange hand gave the reference 1655 its Italian nickname, Freccione, or “big arrow”.

Powered by the same calibre 1575 movement as the GMT-Master, the extra hand traveled the dial once in 24 hours, pointing to its corresponding time on the outer bezel. Unlike the GMT-Master, whose bezel rotated and thus could display time in a second time zone, the Explorer II was meant only to tell its owner whether it was 2:00 a.m. or 14:00 p.m. In the dark underworld of a cave or in the perpetual blackness of the polar winter, time of day can be confused and a reassuring glance at the wrist can be reorienting.

Singular in purpose and entirely uncompromising, the Explorer II was a pure tool.

In the mid-‘80s the Explorer II got a refresh. Its dial added the more familiar circular hour markers and Mercedes handset; the 24-hour hand was reduced in size and painted red instead of orange; a white dial version was introduced. Though it remained the most purely utilitarian watch in the Rolex lineup, some of the magic of the original was lost and the watch languished in display cases, bought only by those who appreciated its minimalist magic, as well as the odd speleologist.

A couple of years ago, ahead of the BaselWorld watch fair a teaser image made its way around the Internet, showing a distinctive orange hand against a white dial. The modernized Rolex Explorer II they subsequently released (amid great excitement) was a huge hit within the watch community. Rolex endowed the watch with a larger 42mm case, solid-link bracelet with an excellent Oysterlock clasp, and blue Chromalight luminescent dial markers for dark polar nights. Most importantly, the new Explorer II returned to the orange hand, driven by calibre 3187, which allows for independent setting of the 24-hour hand for second time zone tracking. There’s also a Parachrom hairspring that provides more resistant to magnetism (like, say, the North Pole). The watch was met with almost universal approval, and though we think it’s probably still not outselling the ubiquitous DateJusts and Subs, it’s evidence that Rolex hasn’t forgotten its tool watch roots. Thank god — and Hans Wilsdorf — for that. We got our hands on a new Explorer II and an ancestor, a rare, straight-handed reference 1655 from 1972. As the photos show, while much has changed, the watch’s adventurous spirit remains.