The fourth-generation Omega Seamaster Planet Ocean 600M is a dive watch in stainless steel. The reference 217.30.42.21.01.001 measures 42 mm in diameter, 13.79 mm thick and 47.5 mm lug to lug, with 21 mm between the lugs. Its satin and polished case has a screw-down crown, a screw-down grade 5 titanium case back with the seahorse emblem and a flat sapphire crystal with anti-reflective coating on both sides. Water resistance is 600 m. The unidirectional bezel has a polished black ceramic insert with a white enamel diving scale and a grade 5 titanium inner ring. The matte black dial has rhodium-plated hands and indices with white Super-LumiNova, four Arabic numerals and no date window. Inside is the Co-Axial Master Chronometer calibre 8912, an automatic movement at 3.5 Hz with a 60-hour power reserve and magnetic resistance to 15,000 gauss, certified by METAS.

Omega presented the redesign at a media event in Miami in November 2025, 20 years after the first Planet Ocean. The new case, profile and bezel are more angular and draw on the Seamaster Ultra Deep and Ploprof. The bezel is wider with 120 clicks, and the helium escape valve of earlier generations has been removed. The steel bracelet has slimmer integrated links, a folding clasp with micro-adjustment and a diving extension. The line also comes on an integrated rubber strap and in versions with blue or orange accents, the orange model costing slightly more. In the US the black dial on bracelet costs USD 9,200; in Europe it is EUR 9,000.

Hodinkee reported that online watch communities were divided within days of the launch. Its own review found the watch comfortable and well proportioned for a 600 m diver, praised the movement, the polished finishing and the bezel’s distinct character, and noted that the black bracelet model costs about USD 300 less than a Rolex Submariner. It criticised the price compared with the 2005 original, the lume being limited to the bezel pip, the 120-click bezel action, a bracelet it found slightly too shiny and the integrated end links. It also questioned the removal of the helium valve when the cheaper Seamaster 300M keeps one. As of October 2026 the fourth-generation Planet Ocean is in regular production.