This chapter introduces an oceanic-vertical perspective on Asia’s Anthropocene, focusing downward from offshore oil platforms to oil fields beneath the seabed. It emphasizes the overlooked role of marine regions in Asia’s contribution to global carbon emissions. It highlights how Asian political elites, particularly after decolonization, played a central role in developing offshore oil fields, synchronizing terrestrial and oceanic energy transitions by the mid-twentieth century. Unlike land-based infrastructures constrained by colonial legacies, marine regions offered greater autonomy, allowing Asian political elites to assert judicial control. The chapter spans from the 1880s to the 1970s, tracing offshore oil’s rise first across Japanese and US waters, later followed by various Asian marine regions. It argues for recognizing Asia’s marine regions as critical sites of environmental transformation and Asian political agency. By foregrounding offshore fossil fuel development, the chapter reframes the Asian Anthropocene within global histories of energy, development, and technology—beyond terrestrial confines and explanations focused on Western colonial and capitalist elites.