This study aims to determine key investment strategies for the performance improvements of the sustainable tourism investment projects. First, the significance levels of experts are computed via dimensionality reduction algorithm. Next, the indicators for sustainable tourism investments are weighted by spherical fuzzy Markov chain. Finally, strategy alternatives for climate-vulnerable destination selection are ranked with spherical fuzzy combinative distance-based assessment (CODAS). Moreover, our ranking results are also compared by using spherical fuzzy ranking technique by geometric mean of similarity ratio to optimal solution (RATGOS). Our findings denote that the improvement of technological infrastructure is determined as the most important factor in the development of sustainable tourism investments. Another important issue in the development of sustainable tourism investments is the determination of environmental priorities. On other side, the optimal strategy alternatives for climate-vulnerable destination selection are financial supports for climate changing and ecological evaluations for renewable energy sources.