The marine environment is under serious pressure from human activities. The transboundary and large-scale nature of these threats require cooperation between states, and between states, industries and NGOs. Marine governance therefore becomes a breeding ground for innovation: multi-level and multi-actor governance and changing spheres of authority. This book applies the concept 'spheres of authority' to investigate the nature of these innovations in governing shipping and offshore oil and gas production. In the environmental governance of shipping, authority is shifting from states that own ships to states that own ports. The environmental governance of offshore oil and gas production shows a shared authority for developing and implementing policies between state and industry, but not a diminishing authority of the state.