Looking for a brawnier beach than Chicago offers? Then head south to this 25-mile sliver of pristine land wedged around the heavy industry of northern Indiana. The 15,000 acres of windswept beaches, dunes, marshes and forests of this National Lakeshore are worth the trip. Though brawny they may look, these ancient glacial dunes form a fragile ecosystem at the mercy of prevailing winds, pounding waves and human encroachment.