What is Speleology?
Speleology is the study of caves and it has been, since the late nineteenth century, its own specific science that is
quite distinct from geography and geology. The leisure pursuit of exploring caves is called potholing or caving but
is occasionally called speleology as a good amount of the actual exploration and research of cave structures has
been done by potholers as part of their hobby.
Not for the faint-hearted, these cavers have to get themselves through some very small spaces and can spend prolonged
periods of time within the cave networks. This can become acutely disorientating, especially when one loses track of
time. Step forward the Explorer II and its 24-hour hand and fixed bezel.
Why the Explorer II?
Designed for speleologists and potholers, the watch afforded such explorers the leveling experience of being
able keep a track of time and whether it was AM or PM via the large luminous 24-hour hand. It also proved useful for
explorers in continents where there were periods of constant daylight or darkness.
The first iteration of the Explorer II was reference 1655, which was powered by the 26-jewel caliber 1575 GMT, the
same movement as in the 1675 GMT-Master. A modified base caliber 1570 movement, the caliber 1575 had a date feature
and the additional 24-hour hand.
The Explorer II had a fixed, non-rotating, bezel with 24-hour markings with the even numbers in Arabic numerals and
odd numbers represented with hash markers. The vintage Rolex collecting community loves nothing more than giving a
watch a nickname and the 1655 is known as freccione (big arrow), which is derived from the large and bold
colored 24-hour hand.
As part of a brand-wide changing of the guard at the end of the 1980s, the Explorer II got a makeover that was inline
with the Daytona, Submariner and Explorer…in fact virtually all of the Rolex watches. The case had a redesign,
including a new bezel that had a new font and triangles to mark the odd hours, which replaced the 1655’s
The large orange hand was also swapped for a more subtle large-pointer hand with red stem and white metal triangle
head. Reference 16550 was a transitional model that existed for two years before the Explorer II settled as
reference 16570. Maybe the biggest change with the five-digit reference Explorer II, however, was the introduction
of a white dial.
Known as the Polar Dial by collectors, the white dials added a whole new element to Rolex sports watches as had never
been seen before. In our mind, the reference 16570 is one of the best value sports Rolex watches in the pre-owned
market. So, go and explore around the depths of our web shop and see if you can uncover the perfect Explorer II for