A few intrepid deer hunters in fall and skiers in winter are just about the only people who visit this Wilderness. A thickly forested swamp with surface water and biting insects, it bears signs of past human influence, such as old logging roads and saw-razed stumps from strip cutting of cedar trees. Swamp conifers, aspens, and white cedars have returned to the region, with red and jack pines standing in its drier areas. Flat to gently rolling, Delirium Wilderness was smoothed by glaciers, which carved six-acre Delirium Pond. Only 300 feet of elevation separate the area's high point from the low point.
The headwaters of the Pine and Waiska Rivers are in the swamp, providing habitat for waterfowl (ducks, loons, herons, and cranes) and small fur-bearing species. Black bears commonly roam the area and rabbits hop through here. There are no established trails, so making your way through these northern wetlands can be physically uncomfortable.