This paper deals with the topic of construction challenges in the karst area and selected three tunnels in the Republic of Croatia, the construction of which is described in more detail below. It describes which problems are encountered during the construction of the tunnel Mala Kapela, Sveti Rok and the tunnel Učka, and on which underground (pits, caves, caverns) or surface (cracks, oysters, sinkholes, bays, fields, plateaus, mounds) are formed karst found. Geotechnical research is of great importance in today's construction, especially in the area of karst, research can significantly facilitate construction work, because their results can give a clear insight into the underground in the area where the work is performed. The course of performing exploratory drilling and seismic research is also described, as well as their characteristics and results that contribute to the prevention of damage during construction. When building a road in the area of karst, you can encounter very big problems that can complicate the performance itself, and certainly extend the construction period due to various morphological phenomena. Some of the problems and challenges faced by tunnel builders in the Croatian karst are the appearance of empty caverns of various dimensions on the route or near the tunnel, the appearance of speleological objects filled with soil and karst and the fall of blocks from the cavern in the tunnel. If it is not possible to carry out geotechnical research before the start of construction, then a very high risk must be taken into account because even in a small area large problems can arise, so the karst is very unpredictable. In most cases, no money is foreseen for previous field research or it is not sufficient, but practice has shown that a subsequently found, for example, cavern can cause greater financial trouble than previous research to prove this cavern.