Two crystal-clear rivers in the most northern part of the Notranjska Park have, with their character, added some Alpine touch to the Notranjska region.
The Iška surfaces on the marshy edge of the Bloke plateau and works its way north through a narrow gorge cut deeply in dolomite. It is fed from both sides by clear streams, the longest and most furcated among them are the Opečnik and the Črni potok streams.

The Zala river surfaces under the Vid plateau. On its way towards the Iška, with which it unites at Vrbica, the Zala has created a picturesque valley with gorge character where numerous rapids, cascades and waterfalls supply the stream with oxygen and make the valley difficult to pass.
The rivers with Alpine character, above which rise steep carbonaceous walls with typical flora, have been included in the Natura 2000 Network because of their intactness and importance for nature conservation.