Kartchner Caverns is a “live” cave, discovered in 1974, and is a stunning limestone cavern with unique minerals and formations. It has an average temperature of 72°F with a 99% humidity year-round so it always feels warm and steamy. Kartschner Caverns State Park is located 9 miles south of Benson on Highway 90. The park is open daily to 5 PM, costs $6 per vehicle to enter the park and $23 for cavern tour per adult. There are two tours: The Rotunda / Throne Tour and the Big Room Tour. The Rotunda / Throne Tour is open every day except Christmas and one week in September for maintenance. The Big Room Tour is open mid-October to mid-April only.