Based on the world record nomination from Europe Records Institute (EURI) and Decision No. WK/USA.INDIA/652/2021/No.108, World Records Union (WorldKings) officially declared Neretva is the world's coldest river on February 6, 2021.
The Neretva begins in the mountains of the Dinaric Alps at 4,026 feet above sea level, where it is formed by the runoff of three large glaciers and by an underground spring situated below the Jabuka Mountain.
Because of this height, even in summer the average water’s temperature doesn’t go higher than 7 degrees Celsius. The cold temperature of the river is concentrated in Upper Neretva.
The Neretva runs a course of 140 miles, 129 miles of which flows through Bosnia and Herzegovina, over a base of limestone and dolomite rock that forms a system of caves and sinkholes. This geological feature means that the Neretva is considered a karst river and is the longest of its kind to flow through the eastern part of the Adriatic Basin. The river is remarkable for its clean, pure water and its deep greenish-blue color.
According to worldatlas