Big Blue (Mason City)

Big Blue, located in Mason City, Iowa, is a freshwater dive site nestled in a 14-acre (5.7-hectare) lake formed from an old quarry. Situated in Lester Milligan Park, this site offers convenient shore access with a maximum depth of 10 meters (33 feet). While visibility varies, it can reach up to 15 meters (49 feet), making it a popular spot for divers, especially on weekends when many gather to explore its unique underwater features. The lake's warm waters and easy entry from the swimming beach make it a great location for both training and casual dives.

Underwater, divers can explore a variety of submerged attractions, including an old training platform at 4 meters (13 feet), several derelict vehicles on the lake's east side, and even a 7.6-meter (25-foot) sailboat. With no gas-powered motorboats allowed, the tranquil environment is often used by local emergency personnel for training exercises. Additionally, the park offers amenities like a shelter house, restrooms, and playground equipment, making it an ideal destination for a family-friendly day trip from nearby cities.