Bastile Lake State Natural Area features an undeveloped wilderness lake surrounded by conifer swamp and a narrow stand of mature hemlock. The 47-acre lake is deep and has extremely soft water. The sparse aquatic vegetation includes pipewort, quillwort, and yellow pond-lily. The fish population is dominated by yellow perch with pumpkinseed, black bullhead, common shiner, and golden shiner. Surrounding the south shore of the lake is a small stand of large old hemlocks with sugar maple, basswood, paper birch, white spruce, white pine, and red pine. The understory includes bunchberry, wood sorrel, and numerous club mosses. White cedar and red maple are common along the shore. East of the lake is a boggy conifer swamp dominated by black spruce and tamarack and an understory of sphagnum moss, Labrador tea, leather-leaf, small cranberry, blue-joint grass, and sedges. The secluded nature of the lake and sufficient forage fish make the lake suitable habitat for nesting common loons. Other birds include belted kingfisher, black-throated green and Nashville warbler, red-eyed vireo, and brown creeper. Bastile Lake is owned by the USDA Forest Service and was designated a State Natural Area in 1996.