Pre-owned Omega Seamaster Planet Ocean 600M Ultra Deep ref 215.30.46.21.04.001 (2023) is one of the most technically ambitious dive watches ever offered to the public, born directly from Omega’s 2019 Five Deeps Expedition. This Ultra Deep is sized at 45.5mm and is constructed from O-MEGASTEEL, a proprietary alloy engineered for exceptional strength and corrosion resistance, and rated to an extraordinary 6,000 meters of water resistance, well beyond conventional professional dive standards. A polished blue ceramic bezel with a white enamel dive scale frames a lacquered white dial, where blue Arabic numerals and 18k white gold hands and hour markers provide crisp contrast and strong luminescence. The domed sapphire crystal and ISO 6425 saturation-diver certification ensure this watch reads true at any depth. An O-MEGASTEEL bracelet with an extendable dive clasp provides a secure, adaptable fit, while the caseback features a laser-engraved sonar medallion in Grade 5 titanium. Powering it all is Omega’s Master Chronometer caliber 8912. Shop OMEGA Seamaster Collection