Haute Horlogerie in a wetsuit: the Fifty Fathoms Tourbillon 8 Jours

Blancpain is highly respected not only for their rich heritage with respect to dive instruments and refined classic watches, but also for their broad spectrum of Haute Horlogerie timepieces. Let’s explore the Fifty Fathoms Tourbillon 8 Jours reference 5025-3630-52B, probably the world’s most complicated dive watch.


This blog essay features various videos in addition to the photos. I think the mesmerizing appeal of a Tourbillon can best be captured in motion, and I hope you will get the best possible idea of this timepiece through the videos.


A timepiece to celebrate both history and present day excellence

Blancpain launched the Fifty Fathoms Tourbillon 8 Jours in 2007 together with the well known Fifty Fathoms Automatique 5015, the Fifty Fathoms Chronographe Flyback 5085 and the Air Command 5885. It has been in the catalogue ever since, available in red or white gold.

The Fifty Fathoms stands firm in the tradition of the world’s first professional dive watch created by Blancpain in 1953. The other tradition incorporated in the Fifty Fathoms Tourbillon 8 Jours is a bit younger, reaching back into the 1980s when Blancpain created the six masterpieces and among those its first Flying Tourbillon.

The watch features the typical 45mm case and sapphire bezel. With a height of 14.7mm the 5025 case is almost 1mm slimmer than the 5015.

To allow full transparency viewing the Tourbillon front and back, the Fifty Fathoms 5025 provides no magnetic shield like the FF 5015. And of course the watch features a display case back with caliber 25A and the Tourbillon fully visible.

Let’s again observe the Tourbillon in action:


A very impressive movement

The automatic winding movement caliber 25A has 223 parts and beats at 3Hz. Variations of this caliber can be found in various Villeret timepieces, in fact this movement has a long tradition within the Blancpain lineup. Caliber 25A has a diameter of 26.2mm at height of only 4.85mm.

The rotor has been designed exclusively for this reference and it shows two plates, fixed with heat blued screws, for the words Fifty and Fathoms. The finishing of the movement leaves nothing to wish for.

As the name of the watch suggests it provides eight days (or 192 hours) power reserve. When I received the watch for the photo session I wound it from zero to 8 days. It took no more than 30 turns to reach the full power reserve, winding is smooth and extremely efficient.

Here’s a short video of the rear view action:


A Grande Complication in a dive watch outfit

At this stage let’s address a key question: is the Fifty Fathoms Tourbillon 8 Jours a sturdy sports watch like the Fifty Fathoms 5015 and ready for any sort of action?

Let’s be realistic, it is not. Consider this: the Tourbillon cage consists of 60 parts with an accumulated weight of 0,2 grams! And it is a Flying Tourbillon, which is probably the aesthetically most impressive execution of this complication, but it also lacks supporting bridges.

A Flying Tourbillon is by definition a delicate mechanism. Held by one screw with a diameter of maybe half a millimeter, one can easily imagine that forces like shocks or lateral acceleration can impact the mechanism.

The Fifty Fathoms Tourbillon 8 Jours provides a water resistance of 300m, so you can swim and of course dive with the timepiece. But it is also a masterpiece of fine complicated watchmaking, so you need to handle it with care.


A convincing aesthetic appearance

Let’s draw our attention away from the Tourbillon for a moment and look at other aesthetic highlights of the timepiece.

The glossy deep black dial distinguishes the 5025 from its 45mm siblings, which feature dials with a sunburst finish.

The indication of the power reserve is not exactly subtle, reminding me a bit of a pressure gauge, offering an optical counterweight to the Tourbillon aperture. Together with the signatures this creates a perfectly balanced dial, distinct from all other Fifty Fathoms models.

The applied arabic numerals and the hands are similar to the other 45mm Fifty Fathoms models. Personally I really like the distortion effect on the numerals created by the domed sapphire crystal, which reminds on shape of the vintage plexiglass crystals.

The beautifully rounded case and the short lugs have been highlighted in various blog posts before. However, in polished red gold those shapes appear even more sensual to me.

Reference 5025 comes with a black sailcloth strap on a heavy and beautifully designed deployant clasp. I only removed its protective stickers for a few photos, so there will be no wrist shots in this essay.



The Fifty Fathoms Tourbillon 8 Jours combines the unrivaled dive watch heritage with the Haute Horlogerie capabilities of Blancpain in a timepiece that works just as well today as it did when introduced in 2007. The watch clearly stands out, it is that kind of configuration you likely won’t find from any other brand.

Of course no dive watch needs a Tourbillon. In fact, the Tourbillon compromises the tool watch character and the ruggedness of this dive watch. But actually that’s not the point about this watch: reference 5025 is primarily a Grande Complication timepiece in a dive watch outfit. And this configuration works remarkably well!

Observing the Flying Tourbillon is an almost hypnotic experience. This complication may have less of a technical impact in a wristwatch than it did in a pocket watch, but it is probably the most impressive visualization of the magic a fine mechanical timepiece can deliver. To conclude this essay, here’s a slow motion video of the Tourbillon:


You find the Fifty Fathoms Tourbillon 8 Jours here on the Blancpain website. A lot of information about the Flying Tourbillon (and the Caroussel) is available in the Lettres du Brassus No. 14.

An overview on the Fifty Fathoms Automatique and all its iterations since 2007 can be found here in the blog. If you like to see other Tourbillon timepieces, here you find two exceptional timepieces in opposite aesthetic translations.

I hope you enjoyed the essay, photos and videos!



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