A relatively under-researched question is whether there is a possibility of influencing environmentally aware tourists regarding ecotourism at destinations that continue to develop under a pattern of mass 'seaside' tourism. Our objective was to assess the pro-environmental intentions of visitors at two small Greek islands, which are within a Natura 2000 site, specifically Paxoi and Antipaxoi. Intentions involved willingness to receive information about the protected area, willingness to accept pro-environmental limitations on recreational experience, and willingness-to-pay a conditional environmental conservation value added tax. In addition, we aimed to identify determinants of visitor pro-environmental intentions among visitor and visit characteristics, visitor satisfaction, and self-reported environmental knowledge, as well as anticipated outcomes of tourism development and suggestions for protected area management. We randomly collected 324 usable questionnaires during the summer season; 242 (74.69 %) by Greek visitors and 82 (25.31 %) by foreign visitors. Visitor satisfaction was quite high; however, visitors reported low levels of environmental knowledge. Our findings showed that the unique characteristics of the destination were not salient among visitors and that there is a lack of effective outreach campaigns, interpretation, and on-site environmental education programs. However, our study revealed high levels of visitor pro-environmental intentions that might support the promotion of ecotourism on the two islands. We provide recommendations based on determinants of visitor pro-environmental intentions, which might assist towards advancing visitor participation in environmental education projects, environmentally responsible behavior among visitors, and financial contribution to environmental conservation by visitors.