HydroConquest

The exact model designation of the HydroConquest is Longines L3.781.4.56.6

The HydroConquest uses the following closure below the wrist: a double-safety folding clasp with integrated dive extension.

The Longines HydroConquest, with a water resistance rating of 30 ATM / 30 bar, is a fully-fledged diver's watch. While standard watches according to DIN 8310 are only tested to the specified value, the diver's watch standard DIN 8306 requires a substantial safety margin, and every watch marked "30 bar" or "300 m" must withstand a laboratory pressure test of 125%. For a 30-bar watch to meet the standard, water resistance alone is not sufficient. The case and movement must incorporate the following protective mechanisms: a rotating bezel with a minute scale for monitoring dive time. For safety reasons, it must only rotate counter-clockwise (to the left) to prevent accidental extension of the dive time. Furthermore, the watch must withstand impacts and strong magnetic fields (e.g., from ship engines) without significant loss of accuracy. Additionally, the watch is immersed in a highly concentrated saline solution for 24 hours. No rust should be visible, and all moving parts (bezel, crown) must function perfectly afterward.