At the steep south foot of the Trnovo forest in the precipitous rocks on the south slopes of Gora, the Hubelj River sources, one of the strongest affluents of the Vipava River. The 5 km long affluent runs through the steep ravine to Ajdovščina however, through the settlement and further to the mouth above Dolenje, it is forced back into the main riverbed. Where it sources, in its upper tract, it preserves natural characteristics and an exceptional picturesque beauty despite human interference. Special characteristics of the sources of the Hubelj, in comparison with other sources in the Visoki (high) karst, are their relatively high position on the slope, as they lie about 100 metres above the bottom of the Vipava Valley, extremely high oscillation of water level and accessible underground canals in dry periods. Today the origin of the name of the Hubelj River still remains veiled in mystery. According to some sources it was named by the Langobards, and its name meant 'torrent'.  
Alongside the Hubelj is a very interesting Natural Science Teaching Path which leads to the source of the Hubelj with its starting point at the Pale sports park. The 3100 metres long path leads us through a mysterious land of nature in the immediate vicinity of the town. We learn about tree species, bushes, stones, the water ecosystem, forest animals and other characteristics and peculiarities of nature. It is interesting to observe the diversity of life on the lowland by the Hubelj river on the dry karstic meadow of Školj.