Imagen: Longines, web oficial
The storyWhy this reference matters
Longines registered the Conquest name in 1954, the first of its families to go through the Swiss intellectual property register — in the fifties, giving a range a surname was still an oddity. Half a century later, in 2007, the company added the Hydro prefix and sent that surname underwater. The HydroConquest reissues nothing, imitates no ancestor from the museum cabinet, and makes no apology for it. In a brand that lives off its archive, that verges on provocation.
The face everyone recognises today isn't the 2007 one. It's the 2018 revision: ceramic in place of aluminium on the bezel, a reworked case, and those applied Arabic numerals at 12, 6 and 9 that identify a HydroConquest from the far side of a table. Ceramic doesn't fade in sunlight or chlorine, which is precisely where the old anodised aluminium gave up. The trade is that one sharp knock against a door frame takes a chip out, and the chip never comes back.
Inside sits the L888, an ETA A31.L11 built exclusively for Longines, which drops the usual 28,800 vibrations per hour to run at 25,200. The swap is deliberate: less frequency in return for seventy-two hours of power reserve. In 2026 Longines redrew the entire collection around 39 and 42 mm cases, with rectangular and triangular markers in place of the big numerals. This 41 is, in all probability, the last of its line.
SpecificationsThe numbers, in one table
| Brand | Longines |
|---|---|
| Family | HydroConquest |
| Reference | L3.781.4.96.6 |
| Years made | desde 2018 |
| Calibre | Longines L888 (base ETA A31.L11) |
| Movement | Automático |
| Frequency | 25.200 alt/h (3,5 Hz) |
| Power reserve | 72 horas |
| Jewels | 21 |
| Complications | Fecha |
| Diameter | 41 mm |
| Thickness | 11.9 mm |
| Lug to lug | 51.1 mm |
| Lug width | 21 mm |
| Case | Acero inoxidable con bisel de cerámica |
| Crystal | Zafiro con tratamiento antirreflejos en ambas caras |
| Water resistance | 300 m (30 bar) |
IdentificationHow to tell it apart
Read the reference in pieces and it tells you almost everything. L3.781 is the 41 mm size, 96 is the blue sunray dial, and the final 6 means the steel bracelet — in the Longines catalogue, 2 is leather and 0 rubber. Blue dial, blue ceramic bezel, bracelet: if any one of the three doesn't match, you're looking at a different reference.
Check the bezel before anything else. It's unidirectional, ceramic, 120 clicks, and the click is dry and audible. Ceramic gives itself away at arm's length: it shines like enamel, the colour has depth, and the figures are filled rather than printed on the surface. A pre-2018 HydroConquest carries a matte aluminium insert that drifts towards blue-grey with age, and it goes first in the first quarter of the bezel.
It measures 41 mm across, 51.1 mm lug to lug and 11.9 mm thick, and it takes 21 mm straps — an awkward width that rules out half of most strap drawers. The case back is solid and screwed down, the crown screws in, and the folding clasp carries around five millimetres of fine adjustment. Watch the second-hand listings: the 43 mm case looks almost identical in photographs and gets advertised as this one.
CollectingWhat collectors check
On the used market the ceramic bezel sets the price. It won't fade, but it chips, and one chip on the edge means a whole new insert. Look at the watch in profile under raking light — that's how nicks show themselves; head-on they hide. The rest of the case wears well, thanks to the mix of brushed and polished surfaces, though a heavy repolish rounds off the chamfer on the lugs and that is gone for good.
Ask for the spare links. The bracelet is screw-adjusted, a big wrist leaves two or three links out of the loop, and those links rarely travel with the watch when it changes hands. Sourcing them later is its own small misery. Check the clasp for play too, and that the crown screws home without any odd resistance: 300 metres depends on gaskets that age, and a pressure test is cheap next to a rusted movement.
The L888 is among the easiest Swiss movements to keep running: it belongs to the ETA family inside the Swatch Group, every watchmaker knows it, and parts are there. One new factor since 2026: with the 39 and 42 mm generation now in the catalogue, this 12-6-9 numeral dial becomes a discontinued face. That guarantees nothing about values, but it does mean anyone will place its era at a glance a few years from now.
Common questionsWhat people ask us about this reference
How water resistant is the Longines HydroConquest?
It's rated to 30 bar, or 300 metres, with a screw-down crown and a screwed case back. That's genuine dive water resistance, not swimming-pool water resistance.
Which calibre does the HydroConquest use?
The Longines L888, an ETA A31.L11 built exclusively for the brand. It runs at 25,200 vibrations per hour and gives roughly 72 hours of power reserve.
Is the HydroConquest bezel ceramic?
It has been since the 2018 redesign. Before that the insert was anodised aluminium, which fades in sunlight and salt water.
Does a 41 mm HydroConquest wear large?
It's 51.1 mm lug to lug and 11.9 mm thick, which is slim for a 300-metre watch. On wrists under about 17 cm, try the 39 mm first.
Keep readingWhere to go from here
Close relativesThe ones it gets confused with
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