It is known that alternative tourism brings travelers closer to nature, while strengthening local communities and traditional products. In recent years, the need arose to try to implement an alternative model of tourism development, so that the negative effects of mass tourism are reduced, and priority is given to issues of balanced development of tourist destinations and preservation of their cultural heritage and identity, alongside the need to develop others beyond the traditional forms of tourism development. In this sense, the purpose of this work is to investigate, both at a theoretical and a research level, the importance of digital marketing in the development of alternative tourism. Specifically, this research aims to investigate in which ways digital marketing can contribute to the achievement of sustainable tourism on the island of Zakynthos, which is an international tourist destination in Greece. Through a literature review, it studies the phenomenon of sustainable tourism and its correlation with digital marketing. Then a detailed case study of the tourism development of Zakynthos and the solutions that digital marketing can provide in its promotion, providing accurate and accessible information on the sustainability of destinations, promoting sustainable travel and tourism habits, and encouraging the adoption of conscious behavior during travel to work toward a more sustainable tourism industry, which is responsible for the environment and local communities.