Outings in nature considered as leisure activity constitute a main way in which many people the world over presently use their free time. Nature is defined here as any natural setting perceived by users as at most only minimally modified by human beings. In its most general manifestation nature thus defined is composed of one or more of six elements: air, land, water, plants, animals (birds, fish) and snow or ice. Outdoor pursuits are immensely popular, especially among city dwellers. They are also widely discussed in leisure studies, where they have inspired considerable research. Still this research tends to lack a theoretic anchor, which this book provides through the new serious leisure concept of nature challenge activity (NCA). It examines several hundred NCAs and types of NCAs, setting out how meeting this challenge unfolds in an aesthetically appealing natural environment with notable implications for consumption and environmental sustainability.