Archaeological data now show that relatively intense human adaptations to coastal environments developed much earlier than once believed—more than 125,000 years ago. With our oceans and marine fisheries currently in a state of crisis, coastal archaeological sites contain a wealth of data that can shed light on the history of human exploitation of marine ecosystems. In eleven case studies from the Americas, Pacific Islands, North Sea, Caribbean, Europe, and Africa, leading researchers working in coastal areas around the world cover diverse marine ecosystems, reaching into deep history to discover how humans interacted with and impacted these aquatic environments and shedding new light on our understanding of contemporary environmental problems.