The purpose of this paper is to theoretically study and investigate the economic impact on the tourism sector in order to draw useful conclusions on how much their overall operation was affected and to map how much they were affected after the Covid-19 period. The empirical research is characterized as a large-scale study that focuses on documenting the operational functions and activities of tourism enterprises in Greece with a focus on the island of Crete. The primary research was conducted using a questionnaire from which the findings were derived. The literature review which formed the basis of the theoretical approach to the topic and the research methodology. The originality of the research is that there is a large sample that answers (135 answers) how many the operational functions and activities of tourism enterprises were affected by the Covid-19 pandemic in Greece. This research requires the participation of tourism enterprises in Greece with the main limitations of the research being the time limitation of the completion of the survey and the geographical limitation in Greece. In addition, a limitation in conducting the survey was the reluctance of tourism business managers to respond to the survey due to confidentiality and privacy issues.