Marine spatial planning constitutes a performative practice whereby territoriality at sea is not only mapped and codified in policy statements but also reworked and re-imagined. The extension of spatial planning to the sea represents an opportunity to develop integrated spatial perspectives cognisant of the diversity of land–sea interactions and transcending existing divisions between maritime and terrestrial policy. Drawing on interpretative policy analysis and critical cartography perspectives, this study examines the spatial imaginaries underlying a particular case of innovative strategic planning at the Dutch North Sea and their capacity to reconfigure existing metageographical understandings of the land and the sea.