Great Lakes, United States offers 1 beach perfect for sunbathing, surfing, swimming, and more. Great Lakes, Illinois, United States, is specifically known for the Naval Station Great Lakes, the largest training station in the U.S. Navy. The best time to travel to the Great Lakes is from June to September, with average air temperatures ranging from 60-80°F and water temperatures around 60-70°F. Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!