Longines HydroConquest Hydroconquest Chronograph Tachymeter

Reference L3.651.4.16.6

About this watch

The Longines HydroConquest L3.651.4.16.6 is a robust and stylish diver's watch that combines performance with elegance. Its 41mm stainless steel case features a rotating bezel, marked from 0 to 60, for precise timing underwater. The sapphire crystal glass is scratch-resistant and adds to the watch's durability. A closed case back limits visibility of the movement but adds to the watch's sturdiness. With a lug width of 21mm, the Hydroconquest comes with a well-crafted stainless steel bracelet that feels solid yet comfortable on the wrist. The chronograph feature is a highlight, providing additional functionality for timing events. The date function ensures you're always on top of your schedule. Whether diving or just out for a casual lunch, this watch feels right at home. Its impressive 300m water resistance makes it a reliable companion for underwater adventures. With a reliable and accurate automatic movement, the Hydroconquest keeps time with impressive accuracy. A power reserve of 42 hours ensures you can take it off for a day or two without worrying about winding it again. The Longines HydroConquest is more than just a watch; it's a statement piece that combines performance with elegance.
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Key Features

  • Longines caliber L667 automatic movement
  • 41mm stainless steel case with rotating bezel
  • Sapphire crystal glass for scratch-resistance and durability
  • 300m water resistance for underwater adventures
  • Chronograph feature for timing events
  • Date function for scheduling
  • 42-hour power reserve for reliability

Specifications

Brand
Longines
Family
HydroConquest
Model
Hydroconquest Chronograph Tachymeter
Reference
L3.651.4.16.6
Movement
l667
Movement Features
  • Hours, Minutes, Small Seconds
  • Date
  • Chronograph
Case
Stainless Steel 41mm
Dial Color
White
Crystal
Sapphire
Water Resistance
300

Current Listings

[WTS] Longines Conquest 39 mm $600 and Longines HydroConquest 39 mm $700

Longines Conquest 39 mm $600 and Longines HydroConquest 39 mm $700

Two Longines watches for sale, the Conquest L3.776.4 and the HydroConquest L3.741.4.

  • Condition: Very good
  • Case size: 39 mm
  • Year purchased: 2025
  • Clasp wear: minor wear on clasp from being stored at work desk
Posted at
Apr 25, 2026, 1:54 PM
Active
[WTS] Longines HydroConquest 41 – $975

Longines HydroConquest 41 – $975

This Longines HydroConquest 41 features a 41mm case, minimal wear, and comes with its box, papers, hangtag, and warranty card.

  • Condition: Very Good Pre-owned Condition
  • Case Size: 41mm diameter
  • Bracelet Condition: hairlines throughout polished surfaces, some desk wear
Posted at
Apr 25, 2026, 10:32 AM
Active
[WTS] Brand New Longines Hydroconquest Exclusive- 42mm- L3.788.4.98.6

Brand New Longines Hydroconquest Exclusive- 42mm- L3.788.4.98.6

Longines - L3.788.4.98.6 · $2,200
The Longines Hydroconquest Exclusive features a 42mm case with a beautiful frosted blue dial and comes in brand new condition.

  • Condition: Brand new, unworn
  • Case size: 42mm
Posted at
Apr 24, 2026, 6:24 PM
Active
[WTS] New Longines HydroConquest 42mm

New Longines HydroConquest 42mm

A new Longines HydroConquest in the 42mm size, with a mesh band and box and papers included.

  • Condition: New
  • Case Size: 42mm
  • Band Type: mesh
Posted at
Apr 23, 2026, 8:54 AM
Active
[WTS] Longines Hydroconquest Chronograph 41 Ref. L3.783.4 – Travel Box & Manual | $1,850

Longines Hydroconquest Chronograph 41 Ref. L3.783.4 – Travel Box & Manual | $1,850

Longines - L3.783.4 · $1,850
The Longines Hydroconquest Chronograph is a high-performance Swiss diver's watch that features a 41mm case, blue ceramic bezel, and screw-down crown. It houses the calibre L688.2, a column-wheel chronograph movement with a 54-hour power reserve.

  • Condition: Very good with minor usage marks
  • Case Size: 41 x 51mm stainless steel case with a thickness of 15.6mm and a lug width of 21mm
  • Movement: Longines L688.2, automatic column wheel chronograph with 27 jewels, 28,800 bph, and a 54-hour power reserve
  • Water Resistance: 300 (30 ATM)
Posted at
Apr 22, 2026, 3:35 PM
Active
[WTS] Longines HydroConquest GMT 41mm Black, Full Kit, June 2025

Longines HydroConquest GMT 41mm Black, Full Kit, June 2025

Up for sale is my mint condition Longines HydroConquest GMT, a full kit with box, papers, tags, and over 4 years left on the factory warranty.

  • Condition: Mint condition
  • Case dimensions: 41mm diameter, 49mm lug to lug, 12.9mm thickness
  • Movement: L844.5 with 72hrs power reserve
  • Water resistance: 300m
Posted at
Apr 19, 2026, 10:47 PM
Active
Longines HydroConquest, L3.781.4.06.9, Steel Diver, Olive, Excellent Condition.

Longines HydroConquest, L3.781.4.06.9, Steel Diver, Olive, Excellent Condition.

Longines - L3.781.4.06.9 · $1,095
This Longines HydroConquest is a steel diver's watch with an olive green matte dial and a unidirectional rotating ceramic bezel. The stainless steel case measures 41mm in diameter and has a water resistance of up to 300 meters.

  • Condition: Excellent Condition
  • Case Diameter: 41mm
  • Thickness: 11.9mm
  • Bezel Type: Unidirectional rotating Green Ceramic
Posted at
Feb 5, 2025, 2:47 AM
Active