While terrestrial archaeology has engaged with contemporary philosophy, maritime archaeology has remained in comparative disciplinary – or subdisciplinary – isolation. However, the issues that humans face in the Anthropocene – from global warming to global pandemics – call for transdisciplinary cooperation, and for thinking together beyond the confines of the human-centered philosophical tradition. Growing areas such as the “blue humanities” and “oceanic thinking” draw directly on our maritime past, even as they ponder the future. Theoretically engaged maritime archaeologists could contribute significantly to these areas of thought, as this volume demonstrates. The essays collected here serve as a jumping off point, which opens new ways for maritime archaeologists to engage with the most important problems of our time and to benefit from the new insights offered by object-oriented and flat ontologies. The book gathers the analytical thinking of archaeologists, philosophers, marine biologists, and media theorists, and pushes those observations deep into the maritime realm. The contributions then branch out, like tentacles or corals, reaching into the lessons of oil spills, cephalopod hideouts, shipwreck literature, ruined monuments, and beached plastics. The volume concludes with a series of critical responses to these papers, which pushes the dialogue into new areas of inquiry. Taken as a whole, the volume emphasizes that the study of the past is more relevant than ever because serious consideration of our transtemporal watery world and all its inhabitants is increasingly necessary for our collective survival. This volume takes the first steps toward this reckoning and, as such, it promises to be an important new contribution to lecture and conference halls around the world where oceans and the Anthropocene are under study.