It flows 380 km (240 mi) from the Coast Mountains southwest to Nass Bay, a sidewater of Portland Inlet, which connects to the North Pacific Ocean via the Dixon Entrance.

[7][8] The English name "Nass" is derived from the Tlingit name Naas which means "intestines" or "guts" in reference to the river's large food capacity in its fish (Naish & Story 1963; Leer, Hitch, & Ritter 2001).

The basin of the Nass is the location of the first modern-day treaty settlement in British Columbia, between the government of that province and the Nisga'a Nation.

The name Nisga'a is a reduced form of [naːsqaʔ], which is a loan from Tongass Tlingit, where it means "people of the Nass River".

If the Tseax Cone were to erupt again, there could be a repeat of the poisonous gas disaster that happened to the Nisga'a people 220 years ago.