A sports watch doesn’t have to be thin. It doesn’t have to fit under a cuff. It doesn’t even have to be pretty. It can be many things, but there are certain traits any watch with sporty ambitions should have.

We’re talking about the likes of water resistance, shock resistance and legibility, among other pragmatic features. Such features were born out of necessity and led to the basic durability that many rightfully expect from nearly any modern watch. Alas, watches today can feel disconnected from their purposeful origins, and many might think of a sports watch merely in terms of its “sporty” design or casual style.

It’s worth remembering where sports watches came from and the core elements that define them. This is instructive to the consumer bombarded with lifestyle marketing as well as insightful for the enthusiast as a window into the history and development of the wristwatch itself. After all, it’s the utilitarian nature of sports watches that makes them compelling in the first place.

Today, the category of sports watches is vast and varied, whereas nearly everything else is relegated to the narrow term “dress watch.” Dive watches, pilot watches, field watches, even many chronographs and GMTs are just some of the most popular examples. While anyone can now wear these watches for nearly any occasion, their history and traits are rooted in very specific applications.

Sports watches are tool watches. They were made for use, worn by athletes, adventurers or soldiers — or for timing the likes of athletic events and even scientific endeavors. They’re watches of action. They were made to endure rough conditions. Sports watches today might be elegant and “sporty” merely in a stylistic sense, destined only to see relatively genteel pursuits and sartorial accessorizing, but even they share that purposeful connection to the past — and, ideally, the same promise of durability.

So, what is a sports watch, exactly? It’s better to ask the question: what should a sports watch do? Here are the basic elements that define sports watches, why they’re important and how they came to be.

A sports watch should be water resistant

For many consumers and even enthusiasts, a watch’s water resistance rating is often seen to quantify its overall toughness. There’s more to durability than that, but they’re not totally off base. Moisture entering a watch case can be fatal to the complex mechanical or electric mechanisms inside, and it spelled the death of many a timepiece before water resistance became the standard feature on watches we now take for granted.

Water resistance isn’t just for dive watches. Watches that never get near submersion are still subject to moisture and particles simply by being part of daily human existence. Just imagine what rust and dust can do to precise clockwork and lubricants. It’s bad news. People today, however, expect to be able to do normal activities without worrying about their watches, like when they wash their hands, brave a downpour, even shower, swim or, yes, scuba dive.

The evolution of water resistance in watches has filled volumes and is fraught with historical discrepancies and controversy among watch nerdery’s most obsessive and academically inclined. What you need to know, however, is that a couple of innovations paved the way for the likes of today’s most popular watches and the extreme examples rated to far beyond what any human can survive.

They’re solutions that are still used today: gaskets and screwed components. That might not sound exciting, but they make exciting sports watches possible. These solutions were developed way back in the 19th century even before watches moved from pocket to wrist in the early 20th. On the wrist, they were even more exposed and increasingly common for the average man. The necessities of war and the popularization of activities like scuba diving accelerated the need to make watch cases as water-tight as possible.

Progress was incremental but there were notable milestones. As early as 1917, during World War I, submarine commanders commissioned a watch called the Submarine produced by the Swiss company Tavannes which was remarkably robust for its time. Rolex famously placed its 1926 Oyster wristwatch on Mercedes Gleitze as she swam across the English Channel in 1927, paving the way for water resistance in everyday watches. The Omega Marine released in 1932 is often considered the first commercially available dive watch. With an elegant, rectangular case, it was hermetically sealed within an outer case.

A new kind of gasket in the 1940s called an O-ring led to more robust watches and the kind of dive watch we know today. Rolex, Blanc and Zodiac all debuted products in 1953 that would be recognizable to us as dive watches, all boasting ratings of around 100m. Dive watches today should usually be rated to about 200m (the equivalent of 20 bar, 20 atm or around 600 feet) or more.

For swimming, you want around 100m, and anything less probably shouldn’t call itself a sports watch. A rating of 50m promises reasonable versatility above water, and you can wash your hands with a 30m “splash resistant” dress watch, but you’ll generally want to baby it more. Watches leave the factory with these ratings, but time and use will erode components like rubber gaskets. Regular servicing is always wise, and assuming vintage dive watches can perform like when they were young is probably unwise.

Today, with advanced machining and tolerances measured by the micron, screwed components such as the crown and caseback have also contributed to ever more extreme products. You can buy and wear watches that are rated to depths which are all but preposterous. Omega holds the record with its 2019 Ultra Deep Professional which was tested to 10,935m and is rated to no less than 15,000m. The commercial version, the Ultra Deep, is rated to a still bonkers 6,000m. It exists among a class of dive watches with extreme water resistance which serve to prove what’s possible and that your watch can survive more that you can possibly subject it to.

A sports watch should be shock resistant

Water resistance in watches is a relatively sexy topic. Shock resistance, on the other hand, can get a bit technical and harder to quantify. But it’s at least equally important and perhaps even more fundamental to a sports watch. At minimum, a sports watch shouldn’t be fragile, right?

Materials and other features contribute to a watch’s overall durability, but when a watch gets knocked around there’s a lot that can go wrong. You might cherish the character and patina of all those little dings on the case, but the movement inside is also under strain. Of all the tiny components that function together precisely, from wheels to springs and even the hands, the most susceptible to shock are the balance’s pivots.

The balance is a mechanical watch’s regulating mechanism. It’s the oscillating wheel with a spring in the middle which provides the characteristic ticking sound and can often be observed through a watch’s caseback window. The famous watchmaker Abraham-Louis Breguet’s pare-chute shock protection dates all the way back to the 1700s, and it was a precursor to the basic system that nearly every mechanical watch uses to protect the balance today.

That system is represented by Incabloc, a spring-loaded mounting for the synthetic jewels which form the balance’s pivot point. Although it was developed in 1934, some watches had essentially no shock protection as late as the 1950s. This system is still used in many watches today, but some brands have also developed their own shock absorption systems such as Rolex with its Paraflex or Seiko with its Diashock. Some brands have taken alternative approaches to further increase shock protection, like Formex with its Case Suspension System in which the case itself moves on springs.

It’s worth noting that some of the most affordable watches are also the most resilient. Casio’s sub-label G-Shock has built its brand around the concept as digital watches with quartz movements have fewer moving parts which can be damaged. Further, lightweight and shock-absorbing plastic cases offer some of the most shock resistant watches available. Other watchmakers such as Richard Mille have hyper-engineered complex mechanical watches with alternative materials for a similar result — if representing the other end of the price spectrum.

In laboratory-like settings, watch manufacturers will often subject their products to stress tests which can be empirically measured. They’ll be dropped from standard, specific heights as well as smacked with a hammer on a pendulum and sent flying into a net. Is it still working? Good. Or: needs improvement. Gung-ho bloggers and YouTubers, on the other hand, will sometimes abuse a watch to the point of its actual destruction. We recommend that you be nice to your watches — but that you wear and enjoy them as they’re intended. Shock protection makes that possible.

A sports watch should be legible — and have strong lume

It’s only in modern times that legibility has seemingly become an “optional” trait in watches. Watches today are worn for different reasons, but in the past they were important tools and most people’s primary way of knowing the time — they were products that needed to be functional, and being able to easily read them was a fundamental tenet of traditional watch design. In many situations, strong legibility was critical.

Imagine you’re flying a plane. But this is no modern passenger jet, it’s a military aircraft in World War II. It’s freezing. You’re wearing goggles. You’re fighting G-forces and air pressure changes. The entire cockpit is vibrating, and this is just on your way to get shot at. You look down at your wrist, and it’s bouncing around with the shaking machinery that surrounds you. No small watch with thin, elegant hands is going to be any use at all.

This is one reason that pilot’s watches tended to be big. Also big were their hands and indexes, designed to be as large, high-contrast and legible as possible at a quick glance — you’ve got a lot of other things to pay attention to up in that bomber, after all. Watchmakers often operating under military contracts probably wouldn’t have guessed that these designs would end up looking so damn cool to their 21st-century descendents. They wouldn’t have cared much, either: their job was producing highly functional and reliable products so that pilots could navigate, among other applications, and return safely home.

Darkness doesn’t help when reading the time, either. You could light up your Zippo to check your Rolex Submariner 6538 like James Bond in the 1962 film Dr. No. But around the time of WWI, watch companies began painting hands and dials with glow-in-the-dark paint made from radioactive radium. It resulted in tragic health consequences for the employees doing so. Later, around the 1960s, the safer alternative tritium was adopted. That’s the meaning of the small “T” or the “H3” in a circle found on some watch dials.

Today, the industry standard is Super-LumiNova or similar materials brands produce and name themselves. They’re quite safe. They absorb light, glow brightly at first, and then usually fade over hours. Watch enthusiasts call this luminescent material “lume,” and they’ll debate and obsess over its brightness, quality and who does it best. Alternatives are tritium gas-filled tubes and electroluminescence. Any watch should be legible, but anything with sports watch intentions should most definitely be reasonably readable in the dark.

Automatic winding is key for mechanical sports watches

Why is automatic winding an important feature for many sports watches? It’s not just about convenience — though, convenient it most certainly is to know that the spring which powers your watch is being wound by the movement of your wrist rather than requiring your regular attention. But there are also very practical reasons that this is a fundamental sports watch feature.

Sports watches are made for use, and made to be relied upon. Knowing that your watch is kept running simply by being worn means that you’ll never have to worry about it running out of power at an inopportune moment — say, while scuba diving or navigating an airplane.

Moreover, many sports watches have screw-in crowns for water resistance (see above). Without automatic winding, you’d need to regularly unscrew the crown to manually wind it. This not only leaves the watch more vulnerable while doing so, but also increases the chances that the crown could be inadvertently left unscrewed. For certain professions that relied on timing it could have been a matter of safety, and it’s one more variable that’s prudent to eliminate.

John Harwood is credited with the first automatic watch in the modern sense, though it was preceded by pocket watch mechanisms in the prior centuries. Harwood’s 1924 employed a weighted rotor which would turn on a central axis with gravity as the watch moved around. The rotor would drive a series of gears connected to the barrel which holds the mainspring powering the watch. Turning the barrel winds the spring.

This is essentially the system most automatic watches use today. Harwood’s rotors would bounce back and forth between springs, however, only turning 270 degrees. Later advancements such as Rolex’s 1931 Oyster Perpetual would see full 360-degree spinning rotors, followed by greater efficiency with those that would offer winding in both directions. The rotor has also become a canvas for decoration and can be seen through display casebacks of many modern watches.

Bonus: Functional bezels add utility and represent the sports watch category

Rotating bezels are the most distinctive features of the most popular sports watches. Far from every sports watch has one, but they merit a mention for being one of the genre’s highly recognizable traits.

What is a bezel? Some consumers might even misunderstand that a watch without a functional bezel has no bezel at all. That’s because it can be a component that might appear to be part of the case. The bezel is a ring that surrounds the watch crystal and, in some cases, used to help secure it. Some watches don’t have a bezel, but most watches do. A bezel can also be decorative with the likes of patterns, textures, finishes, or even the likes of screws or gemstones.

A watch designer can do all sorts of things with a bezel, but they become sporty and arguably most interesting when they’re functional. Even if a bezel doesn’t turn, it can still be functional by carrying scales that are used in conjunction with the watch’s hands and dial. A popular and well known example is the tachymeter, commonly found adorning racing chronographs. It’s used in conjunction with the stopwatch to measure the average speed of a moving object when you know the distance it’s traveled.

Bezels can carry all kinds of scales for different applications. They get really fun and even more useful, however, when they turn. The dive watch’s rotating bezel is the most famous, and it’s used to time minutes, which are critical for divers. A 12-hour scale, on the other hand, can be used for your current time zone but can be turned to provide a quick reference for another locale — without the need of any additional mechanical functionality. GMT watches use an additional 24-hour hand to point along a 24-hour scale, and if that scale is on a turning bezel, it can track yet a third time zone.

The year 1953 is most associated with the kinds of watches that popularized this feature. That’s when Rolex, Blancpain and Zodiac released dive watches featuring it. Many forget, however, that the same year saw Glycine release its Airman which made use of it in a different way: with a 24-hour scale alongside a 24-hour dial. It preceded the Rolex GMT-Master which introduced a 24-hour hand used in the same way, but in addition to the normal 12-hour time — as well as the bicolor design that represented day and nighttime hours, and which would become iconic.

These watches with their rotating bezels, however, built upon those such as the 1937 Rolex Zerographe and the Longines Weems pilot watches, which patented its use before this in 1929. Even earlier, John Harwood had used a rotating bezel with a familiar look for setting and winding. Depending on their purpose, rotating bezels might turn in one direction or both, and they might glide smoothly or ratchet with satisfying clicks. Their visual impact has led to prominent bezels on sportily styled watches such as the Audemars Piguet Royal Oak or Patek Philippe Nautilus, even when they serve no practical function.