ROLEX's "Oyster case," which will celebrate its 100th anniversary in 2026.

In 2026, the iconic Rolex "Oyster case" will celebrate its 100th anniversary.
While "water resistance" is now a given for wristwatches, just 100 years ago, it was not. Instead, wristwatches were delicate, and water and dust were their archenemies. It was an era when even a little hand-washing, rain, sweat, or humidity in daily life often affected the accuracy and lifespan of a watch.

Still, people sought out wristwatches. They were more convenient than pocket watches and left one's hands free. They allowed for quick time checks. To keep pace with the accelerating modernization of society, wristwatches were becoming an "essential tool."
And the moment that wristwatch truly became a "tool" — that's where Rolex's "sealed shell," the "Oyster case," stood.

From here, we will carefully unravel the story of how the Oyster case came into being, the events that astonished the world, and how it evolved over 100 years, continuously supporting Rolex's reputation.

1. What exactly is the "Oyster case"? — A watch that closes like an "oyster"

"Oyster" refers to the marine bivalve.
Just as an oyster protects its contents with a hard shell, the name directly reflects the idea of protecting the watch's internal mechanism (movement) from the external environment.

The core of the Oyster case lies in one point: "preventing water and dust from entering the watch's interior."
However, it's not simply a matter of "making the gaskets thicker" or "filling the gaps." A wristwatch needs a crown to set the time, and the case back must be able to open and close for maintenance and assembly. The crystal also needs to be securely fixed. In other words, it's a design that tackles the contradiction of **"sealing something that has openings and needs to be opened and closed."**

Rolex sought to resolve this contradiction with the mechanical force of "screwing down."
Broadly speaking, the basic philosophy of the Oyster case is as follows:

• Screw down the case back

• Screw down the crown (= stop ingress from the crown)

• Securely fix the crystal (glass) to the case

The "common sense" of modern waterproof watches begins here.

2. Why were watches 100 years ago so vulnerable to water?

Living in the present, it might be hard to imagine a time when "water getting in was normal."
However, due to their structure, wristwatches at the time inevitably had gaps, and daily life itself was a "harsh environment for watches."

• Roads were not sufficiently paved, raising dust.

• Workplaces often had oil, dust, and splashes.

• Hand-washing facilities were not as well-equipped as today.

• Rain gear was not as effective as it is now.

• The idea of "protecting watches from water" was not widespread.

Furthermore, in an era when wristwatches were just beginning to spread, they were not yet trusted as "complete tools."
"Small and convenient, but fragile," "unstable accuracy," "unreliable for daily use"—
such comments were reportedly common.

That's why, to make wristwatches "usable in daily life," accuracy alone wasn't enough. Durability, and water and dust resistance. There was a point in tackling these challenges.

3. 1926: Birth of the World's First Waterproof Watch, the "Oyster"

Then, in 1926, Rolex unveiled the "Oyster" as the world's first waterproof and dustproof wristwatch.
This marks the starting point of its 100th anniversary.

At the time, Rolex was led by its founder, Hans Wilsdorf.
His philosophy was consistent:

A wristwatch should be used daily.
For that, accuracy and reliability are necessary.

Wilsdorf's keen insight lay in his perception that "water resistance is not an added value, but the very credibility of a wristwatch."
A "water-vulnerable watch," no matter how beautiful its appearance or how good its accuracy, cannot be a daily companion.
Therefore, there was no choice but to directly eliminate the watch's weaknesses—and thus, the Oyster case was born.

4. The Legendary Test — A Watch That Swam the English Channel

An indispensable part of the Oyster case's history is the event of 1927.
When British swimmer Mercedes Gleitze attempted to cross the English Channel, a Rolex Oyster was fastened to her wrist.

Crossing the Channel is grueling. Cold seawater, prolonged exertion, waves, salt, impact.
It can be said to be one of the worst environments for a watch.
Yet, after the crossing, the Oyster was still functioning normally—this story has been passed down as a Rolex legend.

What's important here is not just "generating buzz."
For people at the time, water resistance was still a technology beyond imagination.
There were doubts: "Does it really keep water out?" "Is it just advertising?"
Rolex silenced these doubts with the results of the challenge. Rolex knew how to transform the concept of water resistance into "trust."

Rolex widely publicized this event, and people witnessed the "future of wristwatches."

5. The Aquarium in the Shop Window — Changing the Norm by "Showing"

At that time, Rolex also adopted a bold approach in its store displays.
They placed an aquarium in the shop window and demonstrated a Rolex watch operating within it.
While it might seem a bit unique now, it was shocking at the time.

"The watch is moving underwater."
There is no clearer proof.

Technology only becomes valuable when it is understood.
The Oyster case was an excellent invention, of course, but what's remarkable about Rolex is that it made society understand it, desire it, and transformed it into a cultural phenomenon.

6. Water Resistance Alone Was Not Enough — The "Perpetual" of 1931 Drastically Improved Perfection

Even with the birth of the waterproof case, one challenge remained.
That was the "frequency of touching the crown."

A watch needs to be wound. For a hand-wound watch, the crown is turned daily.
Even if the crown is screwed down for water resistance, if it's operated daily, the risk increases.
In other words, for watches with enhanced water resistance, "reducing the number of times the crown is touched" was ideal.

This is where the concept of the automatic winding mechanism "Perpetual" emerged in 1931.
The rotor rotates with the movement of the arm, automatically winding the mainspring.
This significantly reduced the need to touch the crown during daily use, dramatically increasing the completeness of the waterproof watch.

The Oyster case and Perpetual.
The combination of these two established Rolex's position as "the most reliable wristwatch for daily use."

7. The Oyster Case Created "Rolex as a Tool"

When talking about the appeal of Rolex, many words might come to mind: status, asset value, aspiration...
However, at its core is "reliability as a tool."
And it was the "foundation" of the Oyster case that supported this.

And Rolex leveraged this foundation to create "watches for professionals" one after another.

• Water resistance for the deep sea

• Extreme temperature differences in polar regions

• Darkness of cave exploration

• Time zones for international travel

• Race timing

• The harshness of sea voyages

"Rolex's case structure" was brought into every extreme environment.
In other words, the Oyster case is also what took Rolex to "the front lines of the world."

8. Representative Models are also the History of Oyster Case Development

Here, let's look at some representative models supported by the Oyster case, along with the philosophy behind their cases.
(Just listing the model names reveals how the Oyster case has adapted to such diverse environments.)

● Submariner: The Invention of Underwater Use

Moving beyond "waterproof watches" to "diving watches."
Underwater visibility, rotating bezel, robustness.
It's a symbol of how the Oyster case evolved into a "tool of the sea."

● Sea-Dweller / Deepsea: Battling Pressure

In the deep sea, water pressure becomes astronomically high.
To withstand such pressure, the case must not only be "sturdy" but also logically sound in its structure.
Here, Rolex further deepened its case engineering with innovations like the Ringlock system.

● GMT-Master: Air Travel and "Two Times"

Although it seems to be in a different direction from water resistance, it actually relies on a "reliable sealed case" as its premise.
Temperature differences, humidity differences, environmental differences. The robustness of the case is essential for a tool that flies around the world.

● Explorer: The Brilliance of "Looking Normal" in Extremes

A watch for adventure doesn't need to be flashy.
What's important is that it functions "as usual" even in extreme conditions.
The essence of the Oyster case manifests in such aspects.

9. The Philosophy of "Screwing Down" Has Been Refined Over 100 Years

The concept of the Oyster case has been consistent.
"Seal openings by screwing them down."
However, it can be said that the current Rolex exists precisely because this "screwing down" mechanism has been refined for 100 years.

For example, the crown has seen gradual evolution.

• More reliable gasket structure

• Improved sealing power when screwed down

• Improved operability

• Balancing "water resistance and ease of use"

Mechanisms like "Twinlock" and "Triplock," often discussed in relation to Rolex crowns, are also an extension of this evolution.
Precisely because it's a part that users touch daily, Rolex has thoroughly strengthened "the most potentially vulnerable part."

10. Evolution of Materials — Oystersteel and Exclusive Alloys

The Oyster case has evolved not only in structure but also in material selection.
The stainless steel used by Rolex is generally known as a "904L-grade" high-corrosion-resistant material (though there are now many unique terms, including its designation) and is described as being resistant to seawater, sweat, and humidity.
"Water resistance" is not just about stopping water. The exterior's resistance to corrosion also directly impacts long-term reliability.

Furthermore, the development of unique alloys like Everose gold can be seen as a result of pursuing metals that are "practical tools" capable of withstanding daily use, beyond just aesthetic beauty.

11. Water Resistance Does Not Mean "Invincible." That's Why "How You Handle It" Becomes Valuable.

Here's a slightly important point as a blog post.
Waterproof watches are convenient. Rolex watches are very robust.
However, water resistance is not eternal.

Gaskets wear out. If the crown is not screwed down properly, the performance cannot be fully realized.
It's easy to become complacent because they are strong, but ironically, the true value of a "strong watch" comes from "handling it correctly."

• Screw the crown down securely.

• After a strong impact, inspect it just in case.

• Maintain water resistance with regular servicing.

• Saunas and sudden temperature changes can sometimes stress the watch.

These "common precautions" will extend the performance of the Oyster case for a long time.
A technology that has lasted 100 years is also a philosophy for being used for 100 years.

12. What Does the 100th Anniversary in 2026 Mean?

When we hear "100th anniversary," our minds often jump to "Will there be a commemorative model?"
Of course, that's one thing to look forward to.
However, I feel the true essence of the Oyster case's 100th anniversary lies in something quieter and grander.

The Oyster case established "water resistance" as a standard in the watch industry.
And it didn't just promote water resistance; it spread the value that "a watch is a tool for everyday use."
The reason we can confidently wear watches in our daily lives today is because 100 years ago, there were people who created that "standard" from scratch.

2026 is not only a milestone in Rolex's history but also a milestone in the culture of wristwatches.
If the waterproof revolution hadn't happened, wristwatches might have been more delicate and usable only in more limited situations.
The Oyster case elevated the wristwatch to a "tool for daily life"—that is the weight of 100 years.

13. The Oyster Case is Rolex's "Face" and "Backbone"

When talking about Rolex's appeal, there are various entry points: design, accuracy, asset value, iconic status...
However, at its core is always "reliability."

And reliability cannot be built solely with visible hands or dials.
It's the result of accumulated factors: an unseen sealed structure, screw-down mechanism, gaskets, materials, precise machining—all of which allow us to hold a "reliable Rolex" in our hands.

The Oyster case is precisely the backbone of Rolex.
Without it, Rolex would not have become Rolex.
100 years later, that fact seems to remain unchanged.

14. Conclusion: The "Reliability of a Tool" Will Remain Unshaken for the Next 100 Years

100 years ago, it was normal for watches to be vulnerable to water.
A water-resistant watch was almost unimaginable.
But Rolex changed that norm.

The value of the Oyster case is not simply that it is "waterproof."
It lies in its **"making the wristwatch a trustworthy tool."**

In 2026, the Oyster case celebrates its 100th anniversary.
It's not just an anniversary, but a testament to the history of the wristwatch becoming an "everyday companion."
No matter how advanced technology becomes, the essence demanded of a watch—"being reliable"—will not change.
And at the root of that trust, the philosophy of the Oyster case will surely continue to live on for the next 100 years.




ROLEX is here