The Soča (in Slovene) or Isonzo (in Italian) (other names Friulian: Lusinç, archaic German: Sontig, Latin: Aesontius or Sontius) is a 137 km long river that flows through western Slovenia and northeastern Italy. An Alpine river in character, its source lies in the Trenta Valley in the Julian Alps in Slovenia, at an elevation of around 1,100 metres. The river runs past Slovenia’s highest peak, Triglav (2,864 m) before heading south past the towns of Bovec, Kobarid, Tolmin, Kanal ob Soči, Nova Gorica (where it is crossed by the Solkan Bridge) and Gorizia, entering the Adriatic Sea close to the Italian town of Monfalcone. Due to its emerald green water, the river is marketed as “The Emerald Beauty”. It is said to be one of the rare rivers in the world that retain such a colour throughout their length. The Isonzo/Soča is also well known for its unique trout species Salmo marmoratus (known as the marble trout), which lives in the upper course of the crystal-clear river. Source: From Wikipedia, the free encyclopedia.
The upper part of the river and the valley is situated within the Triglav National Park. The Triglav park is the only national park in Slovenia. Within that park there are a lot of beautiful valleys, mountains, forests and many other natural beauties. The valley of the river source is called the Trenta valley and it is one of the most beautiful valleys in Slovenia.