The chapter introduces the concept of Earth’s amphibious transformation—the technological and socio-political extension of the human habitat onto sea surfaces since the mid-20th century. It frames this transformation as a key driver of the oceanic Anthropocene, characterized by intensified vertical interactions with spatial layers above and below the sea surface, reaching from fossil fuels beneath the seabed to outer space. Through oil platforms, wind turbines, mariculture cages, offshore rocket launches, and many other types of artificial islands, marine regions have become central to developmentalist agendas and environmental degradation concerns. The chapter establishes two interrelated analytical perspectives: an oceanic-vertical one that reveals new artificial islands’ upward and downward-oriented access to spatial layers, and a terraqueous-horizontal one connecting these artificial islands to coastlines. Ultimately, reorienting our gaze toward the ocean, the chapter proposes a paradigm shift in recognizing the central role of many marine regions in the Anthropocene, emphasizing artificial islands as both symptom and agent of anthropogenic transformations of planetary scale.