The Blancpain Fifty Fathoms is the larger, more tool-like dive watch with a sapphire-topped unidirectional bezel, while the Bathyscaphe is the slimmer, more everyday sibling with a more restrained look. Both are built around Blancpain's caliber 1315 and a 30 bar water-resistance rating on the references we checked, so the choice comes down to size, character and how often you will wear it. If you want the classic diver's presence, choose the Fifty Fathoms. If you want a diver that slips under a cuff, choose the Bathyscaphe. Bizak & Co. is a sourcing desk, so every watch below is found to order and is not held in stock.
Last reviewed on October 28, 2026 by Filip Biczak. Specifications come from Blancpain's own reference pages; dimensions vary by reference, so confirm the exact watch before you commit. Sources: Blancpain, Fifty Fathoms collection and Blancpain, Bathyscaphe 5000 1110 NABA.
What is the difference between the Fifty Fathoms and the Bathyscaphe?
The Fifty Fathoms is the original, bolder diver; the Bathyscaphe is the compact, subtler one. Blancpain dates the Fifty Fathoms to 1953 and presents it as the first modern diver's watch. Reviewers who compared the pair at the Bathyscaphe's 2013 relaunch described it as a more compact take on that formula, and traced the original Bathyscaphe to 1956. Today Blancpain lists both under the Fifty Fathoms family, which is why the two share so much underneath.
| Feature | Fifty Fathoms Automatique | Bathyscaphe |
|---|---|---|
| Case diameter (examples checked) | 45.00 mm (5015 1130 71S); 42.30 mm (5010 12B40 O64B) | 43.00 mm (5000 1110 NABA); 43.60 mm (5000A 0640 O52A) |
| Case thickness (examples) | 15.50 mm (45 mm steel); 14.30 mm (42 mm titanium) | 13.45 mm (43 mm steel) |
| Water resistance | 30 bar | 30 bar |
| Movement | Caliber 1315, automatic, 4 Hz | Caliber 1315, automatic, 4 Hz |
| Power reserve | 120 hours | 120 hours |
| Bezel | Sapphire-topped unidirectional | Unidirectional, ceramic insert |
| Case back | Solid on the 45 mm steel; sapphire on the 42 mm titanium | Sapphire on the steel reference checked |
| Materials seen | Steel, titanium, gold | Steel, ceramic, gold |
Which one is bigger and which wears better every day?
The classic 45 mm Fifty Fathoms is the larger watch, and the Bathyscaphe is the easier daily wearer. At 15.50 mm thick, the 45 mm steel Fifty Fathoms sits proud on the wrist, while the 43 mm steel Bathyscaphe we checked is 13.45 mm thick. Lug-to-lug distance and strap choice change the feel, so try both on if you can. Smaller wrists often prefer the Bathyscaphe or the 42 mm Fifty Fathoms; larger wrists carry the 45 mm well. Blancpain also makes smaller Fifty Fathoms and Bathyscaphe models, so size alone should not rule either line out.
How do the bezel and water resistance compare?
Both lines are rated to 30 bar on the references we checked, which is enough for serious swimming and recreational diving. The Fifty Fathoms is defined by its sapphire-topped unidirectional bezel, a one-way design so that an accidental knock can only shorten, never extend, a dive time. Check the bezel on any specific Bathyscaphe, because finishes and materials differ by reference.
Do they use the same movement?
Yes, both are powered by Blancpain's automatic caliber 1315 on the references we checked. Blancpain describes it as a 4 Hz movement with 35 jewels, 227 components, a silicon balance spring and a 120-hour (five-day) power reserve. That long reserve means you can leave the watch for a long weekend and still find it running. Servicing needs are therefore the same across both lines, which is useful if you plan to own more than one.
Which Blancpain dive watch costs more?
The Bathyscaphe generally sits in the lower price tier, and the Fifty Fathoms in a higher one, though materials matter more than the model name. Steel and titanium versions sit in the middle of Blancpain's range, ceramic versions step up, and gold versions are in the top tier for each line. We do not quote prices in articles because they move with condition, year and market. For a current figure on a specific reference, browse our Blancpain range or send a sourcing enquiry.
Which should you choose?
- Choose the Fifty Fathoms if you want a bold, instantly recognizable diver with a prominent bezel, or a titanium model for lighter weight.
- Choose the Bathyscaphe if you want a slimmer case, a quieter dial and a watch that works at a desk as well as on a dive boat.
- Choose either if you value the 120-hour reserve and the shared caliber 1315.
Browse our Blancpain Fifty Fathoms models and the Blancpain Bathyscaphe models we can source, or see the full Blancpain collection.
What should you check when buying pre-owned?
Verify the exact reference, the case dimensions, the condition of the bezel and the paperwork, because these differ more between references than between lines. Ask for the reference number so you can match it against Blancpain's own listing, and confirm whether the watch has the box, papers and service history. Check the bezel for smooth, positive one-way action and look for wear on ceramic or titanium surfaces. You can compare options in pre-owned watches or brand-new watches, and our authenticity page explains what we check.
Quick answers
Is the Bathyscaphe a Fifty Fathoms?
Blancpain lists the Bathyscaphe within its Fifty Fathoms family. It is the more compact, subtler model, while the Fifty Fathoms is the classic diver with the signature bezel.
Do the Fifty Fathoms and Bathyscaphe use the same movement?
On the references we checked, both use the automatic caliber 1315 with a 120-hour power reserve, so performance is the same across both lines.
Which is more comfortable to wear every day?
For most wrists the Bathyscaphe, because the 43 mm steel model we checked is thinner than the 45 mm steel Fifty Fathoms. The 42 mm titanium Fifty Fathoms is a lighter alternative.
How water resistant are they?
Both are rated to 30 bar on the references we checked. Always confirm the rating for the exact reference you are considering.
Does Bizak & Co. keep these in stock?
No. We source each watch to order, then confirm the specific unit, photographs and final price before you commit.
Related reading: Blancpain Fifty Fathoms: The Original Dive Watch Compared with Bathyscaphe.
Get your Blancpain sourced
Tell us the model, size, dial and strap preference, whether you want new or pre-owned, and your budget and timing, through our sourcing enquiry form. We confirm the specific watch, photographs and final price before you commit.
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