Diamond Caverns in Park City, KY USA. This is a large and beautiful cave in Mammoth Cave National Park, but privately run.
Location: 1900 Mammoth Cave Pkwy, Park City, KY 42160
Cameras used (3 different visits): Nikon Z7 with Nikkor 24-70 f/4 S lens, Nikon D750 with Nikon 24-120mm f/4 lens, Fuji X-T1 with Fuji 18-55mm lens.