According to the U.S. Census Bureau, the borough has a total area of 40,749 square miles (105,540 km2), of which 35,573 square miles (92,130 km2) is land and 5,176 square miles (13,410 km2) (12.7%) is water. By land area, it is slightly bigger than the state of Indiana.
Its coastline is limited by the Chukchi Sea. The Kotzebue Sound, a significant wildlife area, is a prominent water body within the Northwest Arctic Borough. At Kotzebue Sound was recorded the largest polar bear sighted in history, a male weighing 2209 pounds.
There were 1,780 households of which 55.20% had children under the age of 18 living with them, 47.90% were married couples living together, 19.70% had a female householder with no husband present, and 21.10% were non-families. 16.60% of all households were made up of individuals and 2.10% had someone living alone who was 65 years of age or older. The average household size was 3.87 and the average family size was 4.36.
Age distribution was 41.50% under the age of 18, 10.00% from 18 to 24, 28.10% from 25 to 44, 15.50% from 45 to 64, and 5.00% who were 65 years of age or older. The median age was 24 years. For every 100 females there were 114.50 males. For every 100 females age 18 and over, there were 120.70 males.