The river, which is also called Karlonga or Korna lunga by the locals, is a watercourse with certain characteristics of a stream.

The river originates in the valley under Sveti Anton and flows into the Bay of Koper (in the past, it used to flow into the lagoon of Škocjan). Part of its bed has been regulated artificially in order to provide protection against floods.

In the channel of the river, you’ll also notice kayakers and canoeists from Koper who train here when the sea is rough. Sometimes, they are kept company by coypus or nutria (currently a protected animal species) who have made themselves at home in the area, even though they are not a native species.

The waterfall on the stream of Olmski potok is characterised as a natural asset of national importance.