The Vermillon River has its source at the mouth of Vermillon Lake. The mouth of Lake Vermillon is located in a forest zone in the unorganized territory of Lac-Ashuapmushuan, at:
From the mouth of Lake Vermillon, the Vermillon River flows over with a drop of, entirely in the forest zone, according to the following segments:
northward collecting two discharges of small lakes, crossing Persée lake at the end of the segment, up to its mouth. Note: Lake Persée collecting from the northwest the discharge of Lake Danaé;
towards the north, relatively in a straight line in a steep-sided valley, collecting the discharge of lakes Béost and Oiron, collecting the discharge of a set of lakes including Viau and Recourbé, forming a small hook to the east to collect the discharge of Lake Andromeda, up to a bend in the river, corresponding to the discharge of the lake Moses ;
towards the east, forming a loop towards the north, then bend towards the south-east in order to circumvent a mountain, until a bend in the river ;
first north to a bend in the river; forming a large loop to the east by collecting the discharge of Vacillant lake, collecting nine streams, collecting the discharge of Lake Melincourt; then curving towards the north-west collecting the discharge of Lac des Pinson; collecting the discharge of Lac Maillardet, crossing the Canadian National railway, to a bend in the river;
eastward relatively in a straight line, gradually moving away from the railroad path and collecting the discharge, and cutting the route 167, up to the Fernoël stream ;
forming a loop to the east at the start of the segment, then to the north relatively in a straight line but forming small coils, collecting the discharge of the lakes Julien and Martin, by collecting the discharge of lakes Buvilly and Centaure, by collecting the discharge of lakes Poussard, Canivet and Croche, up to its mouth.
The Vermillon river flows on the south bank of the Chigoubiche River. This confluence is located upstream of a series of rapids, and at:
From the mouth of the Vermillon River, the current descends the course of the Chigoubiche River on, the course of the Ashuapmushuan River on, then crosses the lac Saint-Jean eastward on , follows the course of the Saguenay River via la Petite Décharge on east to Tadoussac where it meets the estuary of Saint Lawrence
