The Green Belt of Fennoscandia (GBF) is a loose concept including nature reserves and various other features depending on the viewpoint. This study explores the use of statistical units, subregions, for defining the Finnish part of the GBF to include these varying standpoints. The analysis indicates that subregions are suitable units for studying and defining GBF from the point of view of the society. Nature protection and development of tourism support each other in GBF, but forest industry – but not forestry – is decreasing in the area. The results also support the use of the extensive delineation (based on subregions) suggested for the Finnish part of the GBF. GBF is a concept and tool for advancing sustainable development and it manifests both principles and practices. As an extensive ecological object when delineated using subregions, GBF also offers plenty of opportunities for national and international co-operation in sustainable development approaches including the topical issue of mitigating the effects of climate change.