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Longines HydroConquest 39mm Mens Watch Black
Ref. L37794566
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Stepping up in the same dial colour
The HydroConquest has been Longines's working diver since the 1960s, and this 39mm version represents a considered refinement of that lineage rather than a reinvention of it. The oversized Arabic numerals of earlier generations are gone, replaced by applied dot and baton indices that read as rather more composed on the wrist — a dial that suits the watch's proportions without sacrificing anything in low light. At 11.7mm thick, it sits unusually flat for a watch rated to 300 metres, which means it passes under a cuff in a way that most divers at this depth rating simply will not. The 39mm diameter puts it at the quieter end of the sport-watch market, and it wears accordingly — closer to a capable everyday watch than something that announces itself. The L888 is the movement worth knowing about here. Built on an ETA base but substantially reworked by Longines, it runs at 3.5 Hz rather than the standard 4 Hz, which is what buys the 72-hour power reserve. The silicon balance-spring adds genuine anti-magnetic resilience and contributes to the stability that earns it Longines's five-year guarantee — extended specifically because they trust this movement to earn it.
- Reference
- L37794566
- Brand
- Longines
- Collection
- HydroConquest
- Case size
- 39mm
- Case thickness
- 11.7mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Black
- Crystal
- Sapphire
- Bezel
- Unidirectional rotating
- Movement
- Automatic
- Calibre
- L888
- Functions
- Date
- Water resistance
- 300m
- Bracelet / strap
- Stainless steel bracelet
- Strap colour
- Silver
- Clasp
- Folding clasp
- Lume
- Super-LumiNova
- Retailer
- Goldsmiths
Additional specifications
- Power reserve
- 72 hours
- Warranty
- 5 years
Learn more about Longines
Auguste Agassiz began trading watches in Saint-Imier in 1832, but the modern company dates from 1860, when his nephew Ernest Francillon built a factory in the meadows beside the Suze — the longines of the local dialect — and consolidated the scattered outworkers of the region under one roof.
Longines registered its winged hourglass in 1889. It is the oldest watch trademark still in continuous use.
The company's identity was built on precision and on timing things in public. It supplied chronographs for the first modern Olympic events it timed in 1896, timed the 1912 Federal Gymnastics Festival with a broken-wire mechanism accurate to a hundredth of a second, and developed the photo-finish camera and the quartz timing devices used across twentieth-century athletics.
Its aviation associations are equally deep. Longines instruments were carried by Charles Lindbergh across the Atlantic in 1927, and the Hour Angle watch, designed to Lindbergh's own specification to simplify longitude calculation, remains in the catalogue. Amelia Earhart and Howard Hughes both navigated by Longines.
The house was among the most decorated at nineteenth-century observatory trials, holding numerous precision records. Since joining the Swatch Group in 1983 it has occupied the accessible-heritage position: exclusive ETA-based movements, archive-driven designs through the Heritage line, and volume that makes it one of the group's most important brands.
- 1860
- Ernest Francillon builds the factory at Les Longines.
- 1889
- The winged hourglass is registered — the oldest watch trademark in use.
- 1912
- Broken-wire timing achieves hundredth-second accuracy.
- 1927
- Lindbergh crosses the Atlantic with Longines instruments.
- 1983
- Becomes part of the Swatch Group.
Manufacturer’s guarantee
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 300m it is rated for swimming, snorkelling and recreational diving.
Will the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Does it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
How long does it run for when it's not worn?
About 72 hours fully wound — enough to sit off the wrist over a weekend and still be running.
Is it a men's or women's watch?
Listed as men's, though at 39mm it sits in the range that suits anyone.
Cheapest place to buy
Goldsmiths is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
Who are Goldsmiths?
Goldsmiths has been selling watches in Britain since 1778 and is part of the Watches of Switzerland Group, which is listed on the London Stock Exchange. They are an authorised dealer, so a watch comes with the manufacturer’s own warranty.
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