Given that its basin reaches only the fringes of the Andes mountains it classifies as a sub-Andean river.

[1] After traveling 180 kilometres (112 mi)[citation needed] Gallegos River reaches the Atlantic Coast.

On its way east, after crossing a 200-kilometre (120 mi) wide glaciated canyon, it meets the tributaries Turbio, Cóndor, and Zurdo.

The river, named after Blasco Gallegos, one of the pilots of Ferdinand Magellan's expedition of 1520, is popular for fly fishing for brown trout, principally by tourists.

Part of the drainage basin of the river lies in Chile's Magallanes Region.