This report a compares environmental NGOs and networks in the Salish Sea with the Baltic Sea area in northern Europe. This analysis conveys that there are more examples of pan-Baltic networks and unions of NGOs, towns, scientific organizations, and SMEs, whose work is supported by national and EU grant programs, than in the Salish Sea. NGOs in the Salish Sea region rely mainly on private donors while Baltic Sea organizations depend on public grants. In Europe, support for cross-border cooperation is mainly motivated by a desire to build a common European identity, which is not the case in Canada–U.S. relations. Civic environmentalism in the form of protests and action groups against environmentally unfriendly activities of companies or governments is more vibrant in the Salish Sea compared with the Baltic Sea. Both in the Salish Sea and Baltic Sea region, universities and the scientific community can be named as leaders of transboundary cooperation.