Sustainability in tourism is a goal and a path that must take into account the needs of visitors, the tourism sector, and communities, as well as the environmental, economic, and social impacts now and in the future. Sustainable tourism must make appropriate use of its territory and natural resources. The green tourism attraction of walkways is becoming very popular worldwide and needs to be studied, particularly in Portugal. The pandemic caused by COVID-19 has profoundly changed consumers’ relationships with tourism. This scientific paper, which has a markedly theoretical and exploratory character, examines the concept of green tourism, highlighting its distinctive characteristics, the environmental and socioeconomic benefits associated with this approach, and strategies for its successful implementation. It also discusses case studies of destinations, worldwide and in Portugal, that have adopted green tourism as an effective strategy for sustainable tourism development. The main conclusions explain that the walkways function as a sustainable tourism system in their economic, sociocultural, and environmental aspects, with a profound impact on the surrounding are, and the Paiva Walkways correspond to the best sustainability practices in terms of green tourism, promoting the participation and involvement of communities in their activities, creating public–private partnerships that add value and share the same values of sustainability, as well as seeking environmental certifications.