Diving into the depths of 40 mm Dive Watches.

Rolex Dive Watch
A closeup of an Omega Seamaster dive watch.

A closeup of an Omega Seamaster dive watch

Buying a watch can be a stress-inducing process. Whether you need a watch for your first-ever deep-sea diving adventure, or just want to add another gem to your collection, it needs to be perfect.

In this blog, we’ll talk about 40 mm dive watches, what characteristics they have, and some of the best 40mm dive watches available on the market today. But first, let’s take a look at the history of dive watches.

Wounding Back to the Beginning

When it comes to dive watches, Rolex was the pioneer that set the stage for the invention of the modern dive watch. In 1926, Hans Wildorf, the founder of Rolex and Tudor, introduced and patented the

revolutionary Rolex Oyster, which featured a water- and dust-resistant (albeit not water-tested) design with a screwed crown, bezel, and a case back.

Not to be outdone, Swiss watchmaker Omega retaliated with the Omega Marine, a watch that could slide in and out of a waterproof case and withstand a depth of 70 meters. A few years later, after some

innovations, the Omega Marine was able to withstand a 135-meter immersion.

World War II

During World War II, Italy’s Officine Panerai commissioned dive watches for the Royal Italian Navy. The watches featured significant cushion-shaped cases, massive winding crowns, high luminosity, and were

water-resistant to 100 feet. These models still serve as the blueprint for the Panerai Radiomir watches.

Then, in 1953, Blancpain unveiled the Fifty Fathoms watches, featuring a 42mm case, a rotating bezel, a black dial with luminescent markers and hands and a depth tolerance of 91 meters — hence the name

Fifty Fathoms. The Fifty Fathoms is still considered the very first modern dive watch. In the same year, Rolex came up with its Submariner, which was water-resistant to 100 meters, beating

the Fifty Fathoms by less than 10 meters, and becoming the deepest-rated dive watch in history.

Omega Seamaster 

In 1957, Omega released its Seamaster 300 dive watch that could withstand 200 meters of water pressure,

as Breitling launched its Superocean collection.

Hence the 1950s were the decade that set the pace for modern dive watches. Since then, watchmakers have continued to outmatch each other and develop models with higher water resistance, sleeker designs, and more durable materials, allowing divers to explore the depths of the ocean.

What Makes A Dive Watch A Dive Watch?

There are a few specific attributes that set the dive watch apart from other watches.

One of the most important characteristics is that they should fit the criteria of ISO 6425 Diver’s watch

standards that stipulate that dive watches should have:

  • A rotating bezel;
  • luminescent features;
  • a screwed crown;
  • a water, shock, and magnetic resistant case and; 
  • water resistance of at least 100 meters.

However, this ISO standard was only introduced in 1996. As we know from the examples of Rolex and Omega, dive watches have been around for much longer than that, so there are plenty of watches out there that are not per ISO 6425. But that doesn’t mean those are bad watches! 

Modern Dive Watches 

What you need to know is that the above requirements are the minimum criteria. Many of today’s watch manufacturers have made models that far exceed ISO 6425, like the Omega Seamaster Planet

Ocean Ultra Deep Professional and Rolex Sea-Dweller. These dive watches have a rotating bezel that tracks the time a diver has been underwater. Some expensive models also show the diving depth.

Additionally, all newer models offer a way to measure the immersion time, often through the bezel, which is marked to 60 minutes. In dive watches, a unidirectional bezel is a fail-safe, life-saving element, because even if it is accidentally manipulated underwater, it will overestimate the immersion/ underwater time. This feature is particularly life-saving as over-immersion can be fatal.

Luminescent features 

The luminescent features on a dive watch allow a diver to quickly read the time at a distance of 25 cm in poor visibility conditions. The deeper you dive into the depths of the sea, the darker it gets, so an excellent luminescent feature makes it easy to know the time. The bezel, hands, and hour marks are all coated in lume paint so that they glow in the dark.

Screwed crown 

A screwed-down crown acts as a water-tight seal, preventing moisture and dust from getting in and tamper with the accuracy or visibility of the watch. This determines how much water pressure your dive watch can handle. A dive watch should withstand a minimum depth of 100 meters.

However, many luxury watches go way beyond that, easily, withstanding depths of thousands of meters. 

For example, the Omega Seamaster Planet Ocean Ultra Deep Professional can resist water pressures of up to 10,928 meters — a historical record, although no human being would survive such depth, let alone reach it. 

Anti-corrosive, Anti-shock material

Dive watches need to be made from a material that does not corrode in saltwater, so most watches are usually made of high-grade 316L austenitic stainless steel, or expensive earth metals like titanium and gold.

Helium escape valve 

Not all dive watches come with helium escape valves, but for deep-sea divers who remain underwater for an extended time, helium escape valves ensure the trapped helium to escape from the watch during resurfacing, maintaining the integrity of the crystal.

Rolex Dive Watch

A 1978 Rolex Perpetual Oyster dive watch.

40 mm Dive Watches and dive watch case diameter

40 mm watches are made for people who have small wrist sizes. For men, a wrist size from 5.5 inches to 6.4 inches is considered to be a small size. A 40 mm dive watch, hence, should have all the characteristics of a dive watch mentioned above and should have the attributes that look good on small wrists. Usually, watches with a case ranging from 38mm to 42mm are suitable for men with small wrists. Typically, watch sizes that are over 46mm look outlandish or overly flashy on any wrist size. For people who have wrists smaller than 6.5 inches, watches with 40mm case are a perfect size.

Watch case thickness 

As the diameter of your watch case increases, so does the thickness of your case. Back in the day, when mechanical watches were trending, a thin case was a sign of superior quality and elegance. However, this is not the case today. Usually, a watch with a small case diameter will have a thin case, while a watch with a 46 mm diameter will have a thick case. Typically, 40mm dive watches have a watch case thickness of about 7 mm. The width and thickness of the case will complement the proportions of your body, so make sure you choose the right size. 

Watch strap width 

A well-proportioned dive watch will have a strap that is half the width of the case diameter. So, for a 40mm watch, the strap width should be no more than 20mm. However, these measurements are not set in stone, and depending on your preference, you may opt for a wider band.

The Best 40mm Dive Watches

Below are a few of the best 40mm dive watches available in the market at different price ranges.

Rolex Oyster Perpetual Submariner

Rolex is the forerunner of dive watches, so it has to be on this list. The Rolex Submariner is a classic among dive watches since it was introduced back in the early 1950s. The watch has since evolved from its utilitarian design to an ultra-modern luxurious timepiece. The Rolex Submariner comes in several different colorways with a 40mm ceramic and platinum bezel and water resistance up to 1000 feet.

Zodiac Super Sea Wolf

The Zodiac Super Sea Wolf is one of the most affordable 40mm dive watches on the market that does not compromise on quality. The Sea Wolf has made many minor upgrades to its pioneer model,

including adding more colorways to the model, making it more appealing. Additionally, unlike many other watches that have a price tag on the lower end of the spectrum, the Zodiac Super Sea Wolf is pretty light and graceful, with a 40mm case diameter and 11mm thickness.

Oris Divers Sixty-Five

The Oris Divers Sixty-Five is another innovative dive watch that features a 40mm case diameter and 13mm thickness. With a depth tolerance of 100-meter, ORIS Diver Sixty-Five may not be for deep-sea divers, but it is a great and more affordable watch for recreational divers.

The Bottom Line 

When buying a dive watch, there are a few factors to consider, including the types of dives you make. If you are a saturation diver, you should consider investing in a watch that holds steady at 1,000 feet or more. 

If not, a watch with a 100 or 200-meter depth tolerance is an excellent choice for recreational and semi-professional divers.

With so many features and gorgeous styles, it is no wonder that divers — and even non-divers — are irresistibly drawn to dive watches. 

Dive watches offer universal appeal and can be worn in the sea and on the land without problems.  If you could only own one high-quality watch, there should be no reason for it not to be a dive watch. 


I'm Leon. I write articles about small watches (usually 38 mm or less in diameter) because I like them. They look stylish and classy to me. Most of the watches on the market today are 40 mm or more, which I think is too big. This blog was born out of curiosity when I was shopping for a small watch myself and couldn't find the info that I needed.

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