The ridge of the Balkan Range is the main watershed between the Black Sea and the Aegean. To the North, towards the river Danube and the Black Sea flow the rivers Vit, Osam and Rossitsa, while to the South, towards the Aegean, rush the Topolnitsa, the Stryama and the Tundja. The deep karst bedrock provides a steady outflow of the underground aquifer feeding those rivers, and the sprawling old forests retain the topsoil moisture. The riverbeds are steep, the rivers are fast and abundant in water.
At many places these rivers jump off high cliffs, forming scenic waterfalls, which the local population calls praskala, or spray gushers. Central Balkan is the scene of some of the highest and most impressive waterfalls in Bulgaria, notably Raiskoto Praskalo (124.5 m.), Vidimskoto Praskalo (80 m.) and Kademliiskoto Praskalo (72 m.).
The gross average annual outflow of all water streams generated in the territory of Central Balkan National Park is 460 million cubic meters; however, this may drop to 290 million cubic meters on a dry year, or rise to 530 million cubic meters on a rainy year. The local water is of very high quality and makes up a large portion of the drinking water resources of Bulgaria.