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Longines HydroConquest 42mm Mens Watch Black Mesh
Ref. L37884706
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Stepping up in the same colour and case shape
The HydroConquest has always occupied a particular position in Longines's catalogue — serious enough for professional diving standards, restrained enough to sit comfortably elsewhere. This reference marks a deliberate shift in how the line presents itself: the large Arabic numerals that used to anchor the dial at three positions are gone, replaced by applied dot and baton indexes on a black lacquered surface, and the rotating bezel now carries a ceramic insert that matches the dial's tone rather than contrasting with it. The overall effect is considerably quieter than earlier iterations. At 11.7mm, it is genuinely slim for a watch rated to 300 metres — most sport divers of comparable depth rating add considerably more height to the wrist, and this one will go under a cuff where many will not. The Milanese mesh bracelet is an unusual choice for the category, softer in wear than a conventional link and adjustable incrementally through the clasp's built-in micro-fit system without any tools. The L888.5 runs on a silicon balance-spring, which means magnetic fields that would disturb a conventional movement leave it unaffected, and its 72-hour reserve is a practical benefit rather than a headline figure — it will return from a weekend without needing to be wound before wearing.
- Reference
- L37884706
- Brand
- Longines
- Collection
- HydroConquest
- Case size
- 42mm
- Case thickness
- 11.7mm
- Lug width
- 21mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Black
- Crystal
- Sapphire
- Bezel
- Unidirectional rotating
- Movement
- Automatic
- Calibre
- L888.5
- Functions
- Date
- Water resistance
- 300m
- Bracelet / strap
- Mesh bracelet
- Strap colour
- Silver
- Clasp
- Folding clasp
- Lume
- Luminous
- Retailer
- Goldsmiths
Additional specifications
- Lug-to-lug
- 51mm
- Power reserve
- 72 hours
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.
What size strap does it take?
21mm. Any strap of that width will fit, and on most modern watches quick-release bars make the swap a two-minute job with no tools.
Will it fit my wrist?
Lug-to-lug is 51mm, which suits wrists from roughly 17.5cm (7 inches) upward.
Lug-to-lug decides fit more than case diameter does.
Is it a men's or women's watch?
Listed as men's.
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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