The Nahwitti River flows northwest from its headwaters near Hashamu Mountain to its mouth on northern Vancouver Island.

The area is underlain by northwest- trending Lower Jurassic Bonanza Group volcanics and sediments and Upper Triassic Karmutsen Formation volcanics and Quatsino Formation limestone, all of which have been intruded by stocks of the Late Jurassic Island Plutonic Suite.

Placer gold is reported near the mouth of the Nahwitti River.