Lion's Den Gorge Nature Preserve is a 73-acre public park along Lake Michigan in Ozaukee County, Wisconsin, near Grafton and Port Washington. Extending about 0.7 miles along the shore, it protects bluffs, a gorge, forest, and wetlands, and adjoins a 44-acre United States Fish and Wildlife Service waterfowl production area. Ozaukee County acquired the land in 2002 from a private owner. More than 1.5 miles of gravel and boardwalk trails wind through white cedar and hardwood forest, wetlands, and the gorge, with some routes climbing nearly 100-foot bluffs and others descending to the lakeshore. The preserve combines public recreation with habitat for native plants, migratory birds, waterfowl, amphibians, and mammals.