The river travels in a south-westerly direction through muskeg and the boreal forest ecozone of Canada[2] The majority of the river and its tributaries are in Saskatchewan with only the final leg being in Alberta.

Several lakes, including Muskeg, Wotherspoon, Matisekawe, Kesatasew, Ethelwyn, and Lost Lakes are within the river's drainage basin.

Part of the western portion of the Mostoos Hills,[3] which are east of Primrose Lake and north of Meadow Lake Provincial Park, are also within Martineau's drainage basin.

The other rivers in the series include Cold River, which drains Cold Lake and flows east and empties into Lac des Îles.

The most common fish in the river include lake trout, walleye, and northern pike.