The Kolpa River is the warmest river in Slovenia, often called the "longest Slovenian Riviera", and is also one of the most pristine and clean rivers in Slovenia.
In the summer months, the Kolpa River measures up to 30 degrees Celsius - which is why it is basic for swimming, kayaking, canoeing, rafting and other water activities.
The river is extremely rich in flora and fauna. Many rare, endangered birds have found a home next to it, especially those tied to the water.
About 20 pairs of gray herons nest near the village of Miliči. Mention should also be made of the otter, which is one of Europe's most endangered mammals. Recent research shows the integrity of nature, as 39 species of indigenous fish have been discovered in the Kolpa River. It is attractive in all seasons; visitors prefer to visit it in the summer months, when it is suitable for swimming.
In the small village of Razloge in Gorski Kotar, below which the river Kolpa originate.
The Kolpa originates in a narrow depth, and the water comes to the surface from a deep karst siphon, which has not yet been fully explored, as divers have so far managed to descend "only" to a depth of 160 meters and originate at 321 meters above sea level. The water temperature is constant throughout the year and is 7 degrees C.
The Kolpa River is the largest tributary of the Sava River in Croatia. The total size of the river basin is 10,236 km2; part of the river basin is located in the Republic of Slovenia, and part also in Bosnia and Herzegovina.