This chapter reflects on marine/maritime spatial planning (MSP) from a Land-Sea Interaction (LSI) perspective. It raises questions about the role and limitations of MSP in addressing sustainable development of the world’s oceans as many of the issues it is concerned with are inextricably connected to activity on the land. The chapter starts by identifying LSI considerations in some of the key documents that are guiding the establishment of MSP. It then sets out a framework for considering LSI and explores the different dimensions with particular reference to examples from European experience. It ends with an exploration of how LSI matters might inform future directions for MSP and may be heralding a new era of Territorial Spatial Planning (TSP), which spans both land and sea.