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

Longines HydroConquest 44mm Black Dial Automatic

Longines - L3.841.4.56.6 · $800

Classic everyday dive watch with a clean black dial, automatic movement and 300m water resistance, perfect for daily wear.

Condition: Good overall
Case size: 44mm
Movement type: Automatic
Bezel material: Aluminum

Posted at

May 22, 2026, 6:21 PM

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Longines Hydroconquest 43mm

Longines - L3.782.4.56.6 · $1,240

The watch is a Longines Hydroconquest model L3.782.4.56.6 with a black dial and a 43mm case size.

Condition: Brand new with minor use (about a month)
Case size: 43mm diameter
Lug to lug length: 53mm
Thickness: 11.90mm

Posted at

May 22, 2026, 4:14 PM

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(brand new) Longines HydroConquest 39mm - $1700 shipped

Longines - HydroConquest · $1,700

This brand new Longines HydroConquest features a 39mm stainless steel case with black dial and ceramic bezel insert, along with a date display at the 3 o'clock position.

Condition: Unworn
Case material: stainless steel
Bracelet material: stainless steel
Water resistance: 300m

Posted at

May 21, 2026, 8:02 PM

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Longines hydroconquest 39 mm green

Longines - hydroconquest 39 mm green · $1,995

This Longines HydroConquest is a recent purchase from a US authorized dealer, still in its original packaging and with all papers.

Condition: great condition
Bracelet condition: has a small ding on the clasp
Box and paper status: all included
Additional strap type: aftermarket rubber

Posted at

May 21, 2026, 9:48 AM

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Longines HydroConquest 39mm Blue – Full Set – Excellent Condition

Longines - HydroConquest 39mm Blue · $1,900

This Longines HydroConquest is a 39mm watch with an automatic movement and ceramic bezel, featuring a blue dial and bezel.

Condition: Excellent Condition
Case size: 39mm diameter

Posted at

May 21, 2026, 4:05 AM

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[WTS] RARE CONFIGURATION Longines HydroConquest 42mm | 2026 Gen | Green Ceramic | Green Lacquered Dial | Ref. L3.788.4.06.6 | Never Worn | Full Kit | Warranty Card 5/8/26

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

Longines - L3.788.4.06.6 · $2,285

This is a rare configuration Longines HydroConquest 42mm watch with a green ceramic bezel and a green lacquered dial. It features an automatic movement, 300m water resistance, and a full kit including the original box, papers, and warranty card.

Condition: never worn
Bracelet: upgraded Longines mesh style bracelet
Movement: Calibre L888.5, automatic, silicon balance spring, 72hr power reserve
Water Resistance: 300m / 30 bar

Posted at

May 20, 2026, 3:53 PM

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