In the past 20 years, children’s declining interactions with nature and outdoor spaces have prompted numerous interventions that aim to promote active outdoor living. This chapter address this development through a focus on coastal areas as a resource for children’s active outdoor living. The chapter presents and discusses research findings from two child-friendly outdoor spaces that have been built with the intention to promote children’s use and motivation for water-based activities. The guiding question is How can tailored outdoor spaces promote active outdoor living amongst children in coastal areas of Denmark? The key findings are that the two new spaces offer highly appreciated opportunities for children to actively engage with outdoor blue spaces through water-based social activities. Specifically, the child-friendly outdoor blue spaces (1) become venues for social interaction, (2) afford challenges and experiences of mastery, and (3) offer a free space away from school, parents, and other expectations and obligations. The outdoor blue spaces offer a special attraction and provide unique opportunities which relate to the history and tradition of outdoor active living in Denmark.