The valleys of the southeastern Žumberak mountain are a representative example of fluviokarst relief in Croatia. Due to the specific lithological base in which dolomites predominate, specific karst and fluviokarst landforms have developed in this area. Geomorphological structures of endogenous and exogenous relief contribute to the great geodiversity of the observed area. The value of geodiversity is partially recognized, although it has not yet been fully valorized and explored. In this paper, a detailed analysis of the relief shaping factors, landscape and morphometric parameters that influence the geodiversity of the southeastern Žumberak mountain was carried out. The aim of the work is to single out the most relevant fluviokarst valley based on the number of characteristic and diagnostic forms of karst and fluviokarst relief in Croatia and to carry out a detailed geomorphological analysis. The method of relative evaluation of the relief singles out areas of greatest value for research and educational purposes. In order to educate the population about the significance of the fluviokarst relief in Croatia, routes of potential educational trails were proposed that would connect the zones of greatest geodiversity. The valley of greatest geodiversity would be a representative example of the fluviokarst relief of Žumberak mountain and as such would represent the unique geoheritage of the Republic of Croatia.