The Tolminka River Valley extends north of the city Tolmin, which is the largest settlement in the Upper Soča Valley, close to the border with Italy. The old town gave its name to the entire Tolmin area as its cultural, administrative and economic centre.
The Tolminka river bubbles to the surface in a delta-shaped karstic spring from beneath the mountains of Tolmin – Tolminski Migovec, Tolminski Kuk, Mahavšček and Rdeči rob. In its short, 10 km long stream the river flows through a glacial mountain valley and then cuts deeply in the wild throughs. In the past, many mills were set up along its tributaries and the river itself was used to transport timber to Tolmin. The surrounding mountain karst areas are dotted with pits and caves, the most known being the Pološka jama cave and the underground system of Tolmin Migovec, which, measuring 27 km in length, is Slovenia's longest cave. Many landslides seen in the valley are a constant reminder that the nature here is ever-changing. During World War I the valley of the Tolminka was one of the areas of Austro-Hungarian army, and flatter parts of the valley were turned into army settlements. The concrete and stone fundations of the barracks settlement are still visible today. The Zatolmin – Polog road was constructed in the same period. In the valley there are well-preserved bunkers from the inter-war period, when the border between Italy and Yugoslavia ran through this area. The bunkers never served their original purpose. The most beautiful World War I monument is a wooden shrine that rises high above the Tolminka riverbed – the memorial church of the Holy Spirit in Javorca.
Steep and forest-clad slopes above the valley are dotted with several mountain pastures where cattle still graze in the summer months. The knowledge of cheese-making, which has through centuries become part of the local culture, and grazing on the flowering meadows guarantee top quality of dairy products. The best known is the Tolminc cheese.