The Soca (in Slovene) is a 138 km (86 mi) long river that flows through western Slovenia (96 kilometres or 60 miles) and northeastern Italy (43 kilometres or 27 miles). An Alpine river in character, its source lies in the Trenta Valley in the Julian Alps in northwestern Slovenia, at an elevation of 876 metres (2,874 ft). The river runs past the towns of Bovec, Kobarid, Tolmin, Kanal ob Soci, 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.Giuseppe Ungaretti, one of the greatest Italian poets, describes the Isonzo in the poem "The Rivers".
The Soca inspired the poet Simon Gregorcic to write his best-known poem Soci (To the Soca), one of the masterpieces of Slovene poetry. This region served as a location for the 2008 Disney film Chronicles of Narnia: Prince Caspian. The Isonzo/Soca 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. This species is endangered due to the introduction of other non-indigenous trout species sometime between World War I and World War II.
