THE REASONS AND SUGGESTED SOLUTIONS OF UNDERDEVELOPMENT OF THERMAL TOURISM IN TURKEYThe main aim of this study is to find out the ways to use geothermal resources efficiently in the thermal tourism sector within the planning perspective. This thesis research has been conducted considering the related issues about thermal tourism such as national and global thermal tourism market assessments, the reasons of underdevelopment of thermal tourism in Turkey, and objectives of thermal tourism planning. In the analysis section, five thermal tourism centers licensed by the Ministry of Culture and Tourism are evaluated according to the technical, physical, and economic feasibility measures and the reasons of underdevelopment of thermal tourism are determined in the cases. In conclusion, the study tries to suggest some solutions to improve thermal tourism sector from the planning discipline.s perspective.