[2][3] The wilderness is forested and flat-to-rolling, with its lower reaches often characterized as a swamp.

Sculpted by glaciers and an ancient glacial lake, it now contains the 80-acre (32 ha) Sylvester Pond and the 6-acre (2 ha) Delirium Pond, as well as parts of the headwaters of the Pine and Waiska Rivers.

[2] Delirium Wilderness is thickly forested with swamp conifer, aspen, and white cedar, with stands of red and jack pine growing in its drier areas.

[2] Wildlife predominant in the Delirium Wilderness includes beaver, bobcat, otter, wolf, various species of duck, loon, great blue heron, and sandhill crane.

Whitetail deer, black bear, and rabbit are also found in the area.