Halleberg is a flat-topped table mountain rising abruptly from the plains east of Vänersborg, forming a pair with the slightly smaller Hunneberg just to the south. Together they make up a protected nature reserve of mixed ancient forest — oak, ash, elm, and lime dominating the lower slopes, giving way to spruce on the plateau. The geology is unusual: the summits are capped with dolerite, a dark volcanic rock that resisted the erosion that wore down the surrounding landscape.
The walking trails are well marked and not strenuous once you've climbed the initial steep edge. The plateau rewards exploration: the forest feels genuinely old-growth in places, and sightings of elk, roe deer, and wild boar are common especially at dawn and dusk. Bring waterproof boots — the plateau collects moisture and is boggy in spring and after rain. The trailheads are accessible by car from the E45 motorway, about 15 minutes east of Vänersborg.