The Nass Basin in west-central British Columbia is an ecoregion of subalpine and montane forests transitional between the interior (leeward) and coastal portions of the Coast Mountains. The climate is humid and cool. The mean annual temperature for the area is approximately 1.5°C with a summer mean of 11.5°C and a winter mean of -9.5°C. Mean annual precipitation ranges from 1500 mm in the lower elevations up to 2500 mm at higher elevations. The region is characterized by forests of western hemlock and western red cedar in the moist montane zone and to a lesser extent lodgepole pine, Engelmann spruce, and alpine fir forests in the subalpine zone. The Nass Basin, composed of folded Jurassic and Cretaceous sediments, is an area of low relief with a gently rolling floor that for the most part lies below 750 m asl. The basin is almost encircled by mountains, but large gaps connect it with the ocean through the Skeena River valley and the Nass River valley and to the interior through the Bulkley River valley. Soils range from Humo-Ferric Podzols and Dystric Brunisols in the montane zone to Dystric Brunisolic and Podzolic soils in the subalpine zone. Characteristic wildlife includes moose, black-tailed deer, woodland caribou, grizzly and black bear, beaver, wolf, red fox, marten, snowshoe hare, and grouse. Land use consists of forest harvesting, mining, hunting, recreation, and tourism. The main communities are Kispiox and Aiyansh. The population of the ecoregion is approximately 1700.
This ecoregion is part of the Pacific Maritime ecozone.