The river rises at a height of on the southern side of Ben More Assynt, and flows just over . The upper valley is known as Glen Oykel (Gleann Oiceall) and is mostly desolate moorland; the lower valley is known as Strath Oykel (Srath Oiceall). The A837 road runs along the river for most of its length, crossing it just above the junction with the Einig, about west of Rosehall at Oykel Bridge. The eponymous hotel is famous among anglers, who are obliged to stay there when fishing the river.