North Fork Koyukuk River, River in Gates of the Arctic National Park, Alaska, US

The North Fork Koyukuk River runs about 105 miles (160 km) from the south slopes of the Continental Divide in the Brooks Range south to join the Middle Fork Koyukuk, 36.5 miles southeast of Wiseman. Its watershed covers 1,850 square miles, and its main tributaries are the Glacier, Tinayguk and Clear rivers.

The name North Fork Koyukuk was recorded in 1899 by T.G. Gerdine of the United States Geological Survey. In 1929 Robert Marshall explored and mapped the river system, naming surrounding peaks including Mount Doonerak, Frigid Crags and Boreal Mountain. Congress designated the river part of the Koyukuk Wild and Scenic River in 1980.

The name Koyukuk comes from the Koyukuk Athabaskan peoples of the region. The North Fork was recorded in 1899 by T. G. Gerdine of the United States Geological Survey. In 1929 Robert Marshall travelled the river system and named surrounding peaks, including Mount Doonerak, Frigid Crags and Boreal Mountain.

Reaching this river requires using a flight service from Bettles or Coldfoot, as there are no roads to the area. Visitors should come well prepared and understand that boat trips feature varying water conditions, from calm stretches to faster rapids.

Robert Marshall explored and mapped the river system in 1929 and named Frigid Crags and Boreal Mountain, the two peaks whose paired form gave Gates of the Arctic its name. The North Fork joins the Middle Fork 36.5 miles (59 km) southeast of Wiseman to form the Koyukuk main stem.