Longines HydroConquest Hydroconquest Automatic 42 Stainless Steel / Frosted Blue / Mesh

Reference L3.788.4.99.6

Longines Hydroconquest Automatic 42 Stainless Steel / Frosted Blue / Mesh

About this watch

The Longines HydroConquest L3.788.4.99.6 debuted in 2026 as part of the HydroConquest collection, Longines’ line of contemporary dive watches designed for professional water resistance and everyday durability. The model follows the design direction introduced with the HydroConquest GMT in 2024, which revised the collection’s dial layout and finishing. The round stainless steel case measures 42 mm in diameter and is equipped with a screw-in crown and a unidirectional rotating bezel fitted with a black ceramic insert. Water resistance is rated to 30 bar. The watch is fitted with a scratch-resistant sapphire crystal with several layers of anti-reflective coating applied to both sides. The dial is executed in frosted blue with a sunray finish. Applied indexes serve as hour markers, reflecting the updated HydroConquest design that no longer features Arabic numerals on the dial. Silvered polished hands indicate the time, while a date display completes the functional layout. Power is provided by the Longines calibre L888, a self-winding mechanical movement beating at 25,200 vibrations per hour. The movement is equipped with a monocrystalline silicon balance spring and offers a power reserve of approximately 72 hours. It drives the central hours, minutes, and seconds together with the date indication. The L3.788.4.99.6 is fitted with a stainless steel bracelet in a Milanese mesh style, secured by a double security folding clasp with a micro-adjustment system.
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Specifications

Brand
Longines
Family
HydroConquest
Model
Hydroconquest Automatic 42 Stainless Steel / Frosted Blue / Mesh
Reference
L3.788.4.99.6
Movement
l888-2
Movement Features
  • Hours, Minutes, Seconds
  • Date
Case
42mm
Dial Color
Blue
Crystal
Sapphire
Water Resistance
300

Current Listings

[WTS] Longines Hydroconquest 39mm black bezel/dial

Longines Hydroconquest 39mm black bezel/dial

Longines - 39mm black bezel/black dial Hydroconquest · $2,200
This Longines Hydroconquest 39mm features a black bezel and dial, is in excellent condition, and comes with its full kit including boxes, hangtags, warranty card, and owner's manual.

  • Condition: Like-new
  • Case size: 39mm diameter
  • Box status: full-kit
  • Warranty remaining: five years
Posted at
May 16, 2026, 5:17 PM
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[WTS] Longines HydroConquest Two Tone Green Dial $1499

Longines HydroConquest Two Tone Green Dial $1499

Longines - HydroConquest · $1,499
Longines HydroConquest Two Tone Green Dial for sale

Posted at
May 16, 2026, 11:33 AM
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[WTS] Longines HydroConquest 42mm | 2026 Gen | Green Ceramic | Green Lacquered Dial | Ref. L3.788.4.06.6 | Never Sized, Never Worn | Full Kit | Warranty Card 5/8/26

Longines HydroConquest 42mm | 2026 Gen | Green Ceramic | Green Lacquered Dial | Ref. L3.788.4.06.6 | Never Sized, Never Worn | Full Kit | Warranty Card 5/8/26

Longines - L3.788.4.06.6 · $1,999
This is the first real redesign the HydroConquest has seen in nearly a decade with thinner case and upgraded ceramic bezel with audible click.

  • Condition: Never sized, never worn
  • Movement: Calibre L888.5, automatic, silicon balance spring, 72hr power reserve
  • Water resistance: 300m / 30 bar
  • Box papers: Full double-box set with instruction manual and tags present
Posted at
May 16, 2026, 10:58 AM
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[WTS] Longines Hydroconquest 41mm Black dial

Longines Hydroconquest 41mm Black dial

Longines - L3.781.4.56 · $1,100
A Longines Hydroconquest 41mm with a black dial is being sold. The watch features an original box and bracelet, as well as two additional straps.

  • Condition: Very good condition, a few scuffs on the sapphire but no scratches
  • Case size: 41mm
  • Bracelets: 2
  • Straps: 2
Posted at
May 15, 2026, 2:06 PM
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[WTS] Longines Hydroconquest 39mm L3.779.4.96.6

Longines Hydroconquest 39mm L3.779.4.96.6

Longines - L3.779.4.96.6 · $2,100
A Longines Hydroconquest 39mm with a frosted blue dial, this watch features a unique and stylish design.

  • Condition: Like new
  • Size: 39mm diameter
Posted at
May 14, 2026, 10:43 PM
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[WTS] Longines Hydroconquest 39mm

Longines Hydroconquest 39mm

Longines - HydroConquest 39mm · $2,000
A Longines Hydroconquest diver's watch in excellent condition, featuring a 2026 movement and virtually no signs of wear.

  • Condition: 9.6/10 - extremely clean example
  • Movement: 2026
  • Case condition: virtually no signs of wear
  • Box included: true
Posted at
May 14, 2026, 10:36 PM
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[WTS] Longines Hydroconquest 39mm Limited Edition Commonwealth Games Mint

Longines Hydroconquest 39mm Limited Edition Commonwealth Games Mint

Longines - L3.779.4.09.9 · $2,950
A limited edition Longines Hydroconquest, purchased just a week ago and still under warranty.

  • Condition: Mint
  • Case Size: 39mm
  • Limited Edition Quantity: 2026 pieces
  • Warranty Length: five years
Posted at
May 12, 2026, 4:37 PM
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[WTS] Longines HydroConquest 39mm Automatic Black Ceramic Bezel + Bracelet + WOE NATO - $750

Longines HydroConquest 39mm Automatic Black Ceramic Bezel + Bracelet + WOE NATO - $750

Longines - HydroConquest 39mm · $750
This Longines HydroConquest is an excellent daily-wear diver with great proportions and comfortable sizing, featuring a black dial and ceramic bezel. The watch is running well and keeping great time.

  • Condition: Excellent daily-wear, shows wear from use on the bracelet
  • Case Size: 39mm diameter
  • Bracelet Type: black ceramic bezel + bracelet + WOE NATO
Posted at
May 12, 2026, 4:18 PM
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[WTS] Longines Hydroconquest Quartz Two Tone L3.740.3.56.7 - $600 🚢

Longines Hydroconquest Quartz Two Tone L3.740.3.56.7 - $600 🚢

Longines - L3.740.3.56.7 · $600
A quartz-powered diver's watch from Longines, featuring a black dial and two-tone yellow gold PVD finish on the 41mm case.

  • Condition: Good (light scratches)
  • Case size: 41mm
  • Material: two tone yellow gold PVD
  • Movement: quartz
Posted at
May 10, 2026, 5:48 PM
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