An historic lighthouse and associated support buildings are located on one of the islands, owned by the Coast Guard as an inholding in the wilderness area. All three islands are composed of sand and gravel on a glacial boulder base. Show Island is often overtopped by storm waters and is devoid of tree growth. Pismire supports both tree and shrub life. Both islands support colonial nesting gulls.
Scarecrow Island is composed of glacial boulders and gravel with a rocky substrate.
Numerous shrubs and trees support nesting heron and cormorant colonies. The Agassiz wilderness was established in 1976 and contains approximately 4,000 acres. Located in the extreme northwest part of Minnesota, on an ancient embayment in the bed of glacial Lake Agassiz, the Agassiz wilderness is situated in a narrow ecotonal zone between grasslands to the west and deciduous forest to the east. This wilderness area is a large peninsula of bog and timber habitat lying between three major refuge water impoundments. Covered with blackspruce and tamarack, and surrounded by aspen and willow, this community represents one of the most westerly extensions of this forest type in Minnesota.