The Samur river originates in glaciers and mountain springs of the Greater Caucasus mountains. It rises in the northeastern part of Guton Mount at an elevation of 3,648 m (11,969 ft). Descending from the mountains for 7 km (4.3 mi), the river receives its tributary the Khalakhur River flowing down from an elevation of 3,730 m (12,240 ft). The length of the river is 216 km (134 mi), its basin 5,000 km2 (1,900 sq mi). The elevated and midsections of the river from through the territory of Russia, lower sections flow through Azerbaijan making up the Russian-Azerbaijani border. After joining its other tributary Usuxçay River, the width of the river grows.
Once the river is in the open Caspian basin, it splits some of its parts into Tahirçay (34 km (21 mi)) and Uğar 28 km (17 mi) rivers on Azerbaijani territory. The river mainly feeds on rain and underground waters with its volume broken up as follows: 42% from rain, 32% from underground waters, 22% from snow, 4% from glaciers. The river supplies irrigation water to Samur-Absheron channel which follows south to Jeyranbatan reservoir.