Pre-owned Omega Seamaster Planet Ocean 600M ref. 217.30.42.21.01.003 (2026). The Planet Ocean has been Omega’s heavy-duty dive watch since 2005. While the Seamaster Diver 300M often gets most of the attention, the Planet Ocean has always been the more serious tool watch of the two, with greater water resistance and a more rugged overall design. For 2025, Omega gave the collection its first major redesign in years. The changes are immediately noticeable. The case has a sharper, more angular shape, and for the first time, the familiar lyre lugs that connected the Planet Ocean to the rest of the Seamaster family are gone. Omega also retired the helium escape valve, a feature that had been part of the Planet Ocean’s identity since day one. Beneath the crystal is another interesting update borrowed from the Ultra Deep collection: an internal titanium support ring that strengthens the case while remaining completely out of sight. The dial, however, is still very recognizable. A matte black surface provides excellent contrast for the broad arrow hands, oversized hour markers, and Arabic numerals at 3, 6, 9, and 12. The ceramic bezel has also been redesigned with deeper grip surfaces and a cleaner diving scale. Shop OMEGA Seamaster Collection