The topic of the present research is the pilot estimation of sustainable tourism indicators for the Municipality of Hersonissos in Crete. Indicators definition is based on the principles of sustainable development. Data sources, their format and functionality as well as limitations imposed by them regarding indicators estimation, are elements of this research. Moreover, indicators were examined in terms of their functionality, resulting in certain cases, in the definition of surrogate indicators in order to compensate the lack of data and complement their meaning respecting the needs of the application area.