Longines HydroConquest 39mm Blue vs Longines HydroConquest 39mm

Both are 39 mm Longines HydroConquest divers with the same 300 m rating, sapphire crystal, ceramic bezel and roughly 72 hours of power reserve, so the real choice is dial color and movement generation. The blue L3.780.4.96.6 uses the L888, while the grey L3.780.3.78.6 lists the L888.5, a later silicon-balance variant that resists magnetism better. Owners praise the compact 39 mm case and the bracelet; the main complaints are the clasp bulk and the bezel action being firm. Buy the grey if you want the newer movement and a quieter look; buy the blue if you want the classic diver look.

• Choose the blue HydroConquest if you want the classic sunray blue diver dial and the proven L888 movement.
• Choose the grey HydroConquest if you want the later L888.5 movement and a more subdued dial that pairs with more outfits.