The first of Tubutulik River, like the lower course of the Fish River, is a tortuous channel through alluvial flats built out from material that it brought down from its upper course. After the flats, there is a more restricted valley with the high hills of the Cape Darby granite area to the west and the softer forms of the limestone and schist on the east. Its course passes the mouth of Chukajak Creek. Vulcan Creek and its tributaries enter the main river from the west. Vulcan Point is located on Vulcan Creek. Continuing upstream on the Tubutulik is the lower end of a narrow canyon. Above the canyon, the stream valley broadens out again into a basin of a smaller area but otherwise similar to that of Fish River and is connected with the latter by a low pass used in winter in making the overland trip from Golovnin Bay to Kotzebue Sound. The limits of this basin can be seen from the Bendeleben Mountains. A sand spit lies opposite the mouth of the river.