The Michigan DNR says (in part from this PDF) that Grand Sable Lake:
…is a scenic undeveloped lake located in Alger County, about 6 miles southwest of Grand Marais. The 630 acre lake lies within the boundaries of the Pictured Rocks National Lakeshore (PRNL). The shoreline is mostly wooded with mixed hardwoods, conifers, and cedar species. Most of the surrounding soils are sandy. Sand dunes 200 ft high are located on the north end. Grand Sable Lake has a maximum depth of 85 feet, but averages around 35-40 feet. The banks drop off quite rapidly. Even so, the shoreline at the public access site on the northeast shoreline remains shallow for over 200 feet, dropping quickly into deep water…
Access to the lake before the area became part of the PRNL was from the small park on the north end. At that time, the park was managed by the village of Grand Marais. A 1949 fisheries survey documented the presence of rock bass, northern pike, yellow perch, smallmouth bass, white suckers, and minnow species. Past stocking efforts included rainbow trout, splake, smelt, smallmouth, largemouth, pike, bluegills, and lake trout.
Much (much) more from the awesomely amazing Pictured Rocks National Lakeshore on Michigan in Pictures!