The Omega Seamaster Planet Ocean reference 2200.51.00 represents the original 45.5mm Big Size execution of the Planet Ocean line that launched in 2005 as Omega's modern dive flagship, the larger case anchoring the collection alongside the 42mm and 39.5mm references that followed. The 45.5mm stainless steel case carries a unidirectional rotatable bezel with a black aluminum insert and 60-minute diving scale, paired with a black lacquer dial featuring broad applied luminous indices, Omega's signature arrowhead hour hand, and a date window at three o'clock. The case construction includes a screw-down crown and helium escape valve protecting 600 meters of water resistance, the depth rating that gave the original Planet Ocean its name. Powered by the Omega Caliber 2500, the brand's first Co-Axial production movement based on ETA 2892-A2 architecture modified with George Daniels' Co-Axial escapement, beating at 25,200 vibrations per hour with a 48-hour power reserve. Sapphire crystal with anti-reflective coating, fitted on a brushed and polished stainless steel bracelet. The 45.5mm 2200.51.00 represents the original Big Size Planet Ocean and now sits as a sought-after vintage execution of Omega's modern dive flagship. 2011 production, pre-owned condition.