It heads into the Northern Rocky Mountains Provincial Park, and flows northeast and then east into the Muskwa River.

In the area around Tetsa River there are mainly pine forests.

The area around Tetsa River is almost uninhabited, with less than two inhabitants per square kilometre.

The neighbourhood is part of the boreal climate zone.

The warmest month is July, with an average temperature of 13.5 °C, and the coldest is January, -15.9 °C.