Dunn Lake features a mosaic of communities surrounding the lake, giving the area a wilderness aspect. The site contains an outstanding example of northern mesic forest, with super-canopy white pine above large hemlock, yellow birch, sugar maple, and basswood. This undisturbed stand lies on the northeast side of Dunn Lake and extends eastward across the Presque Isle River. Another old-growth stand lies on an upland peninsula west of Sanborn Lake. The Presque Isle River is a meandering, soft, warm water stream that supports a high diversity of native aquatic plants. Bordering the stream are excellent examples of northern sedge meadow, alder thicket, and northern wet forest communities. Recent beaver activity has altered the composition of these. The uplands to the south have been subjected to intensive timber harvest. Bald eagles have nested in the large white pines. Dunn Lake is owned by the DNR and was designated a State Natural Area in 1990.