Sea cities are at the forefront of climate change. Globally, the developed coastline of many cities is at high risk of sea level rise, coastal flooding, and storm surge. Such risks, however, can turn into important opportunities for re-imagining the future of cities and their resilience and sustainability. Despite being controversial, unsettlement, re-settlement, retreat, temporary and permanent relocation, and climigration are concepts that are rapidly becoming an inevitable urban policy and planning consideration. Yet, the idea of a nomadic city, a city that moves, is not new. In fact, the oldest forms of human adaptation to coastal hazards have been through relocation to higher grounds. While temporary forms of relocation have long been prominent in disaster risk reduction efforts, permanent retreat and relocation of urban communities are increasingly becoming critical discussions in climate change adaptation. This chapter focuses on urban resilience to coastal hazards and explores strategies ranging from temporary retreat and managed retreat to migration as a land use policy that can create transformative opportunities for adaptation and re-imagines the future of sea cities in a changing climate. Case studies from around the world are presented, exploring the potential of policy responses as well as the key barriers and drivers for their implementation.