Occasionally in life, knowing how high you are above sea level is very important. But finding an analog altimeter on a mechanical watch is a pretty rare thing. They do, however, exist.
Part of the problem of installing relatively old technology into a wristwatch comes down to miniaturization. Modern materials have enabled a handful of watchmakers such as Breva, Oris, and Favre-Leuba to get around the age-old problem and roll out some pretty nifty gadgets that can keep track of your ascending and descending when far from the reaches of GPS.
Watches fitted with GPS connectivity can provide an altitude reading based on location. Satellites pinpoint you on a map and then draw that information from a database. Watches like this do not actually read the altitude, they simply refer to a massive bank of information that already exists.
Advantageously, this kind of reading is impervious to atmospheric changes caused by weather. Calibrating any mechanical altimeter is essential, but these readings can be massively affected by a shift in conditions. A GPS-driven altimeter does not suffer from the same problem because its technology need not be exposed to the elements.
The downside is that GPS watches need a signal to work and, rather ironically, you are most likely to need an altimeter in areas of poor (or no) signal. For that reason, there is a place in the world of mechanical watchmaking for good quality altimeters. But, in the past, these have been expensive and difficult to find.
One of the first mechanical altimeters to hit the market was made by Breva back in 2014. The Breva Genie 02 Altimeter was a stunner and looked every bit the luxury interpretation of a practical timepiece. But with a price tag of $132,000, it was far from practical, and even further from being accessible.
Fast forward two years and Oris, available on Jomashop.com, released the Oris Big Crown ProPilot Altimeter, which retailed for less than 4k, suddenly opening up the world of mechanical altimeters to the buying public.
Soon after, Favre Leuba debuted the Bivouac 9000. A hulking timepiece with an intuitive and creative display, its ascent to the summit of Everest (within its 9,000m limit) was a strong statement of its ability and a new benchmark in the world of mechanical altimeters.
The way these watches work is truly fascinating, with the technology sounding almost unbelievably delicate. Fitted inside the case is an aneroid capsule, which expands and contracts depending on the external air pressure. For this to work, there needs to be a gap in the case, which is not very helpful for maintaining water resistance. Some models use perforations in the case back, which very much limits the resistance of the piece to water ingress, while others require the crown to be unscrewed for the altimeter to become functional.
Although not ideal, the latter solution does mean that water resistance can be "re-activated" when the altimeter is not in use, but it does make ad hoc use effectively impossible.
Some of the best altimeters on the market use digital quartz modules instead of mechanical movements for the timekeeping side of things. This frees up a lot more internal space for the necessary pressure-testing components. Casio (and the Pro-Trek sub-brand) offer a wide range of digital watches fitted with altimeters (as well as other useful adventure tools such as barometers (which function along very similar lines), compasses, and even thermometers).
The Casio Pro Trek Perpetual Alarm World Time Chronograph (reference PRG-240T-7DR) is a particularly strong release boasting excellent value and high functionality. For a Swiss alternative, check out the Tissot T-Touch range. Models such as the T Touch Expert Solar II Analog-Digital Men's Watch (T110.420.47.051.00) offer excellent aesthetics and a wide range of functions for less than $1,000.