Abstract: The region of Southern Dinarides is one of the most karstified areas in the world; an area endowed with the highest precipitation in Europe. The soluble carbonate sediments are more than 300 m thick. The average depth of karstification ranges from 250 to 350 m and locally, along the deep faults, even deeper. Average underground flow velocity varies within a wide range from 0.002 to 55.2 cm/s. Ground water residence time is very short. Fluctuations of the water table are very fast with amplitudes up to 312 m. After high precipitation, the water table responds in less than four hours. The major characteristics of large karst springs are deep siphonal outlet channels and large variation of minimum and maximum discharge. Thousands of ponors (swallow holes) and estavelles have been registered in this area. Swallowing capacity of some of them is more than 100 m3/s. The large and temporary flooded karts poljes are world wide known karst features. Due to very complex hydrogeological and political circumstances at the area of Southern Dinarides, there appears to be a very sensitive problem with transboundary aquifers. Questions regarding hydro potential utility, water supply and environmental impacts are critical and are in need of proper answers. Changing of natural spring discharge and the survival of wildlife, particularly endanger of endemic species, have been key topic of many recent karst related engineering projects. In general, all problems can be classified as those related to the water quantity and water quality. Newly established state borders at the South Dinaric region invoke a number of questions related to the newly established transboundary aquifers.