Kartchner Caverns State Park

In November 1974 two young cavers exploring the limestone hills at the eastern foot of the Whetstone Mountains found a narrow crack at the bottom of a sinkhole. Warm, moist air was flowing out of it, a sign of a cave, and after hours of crawling they reached an untouched cavern. They kept it secret until February 1978, when they told the landowning Kartchner family, and the secret held through years of quiet negotiation with Arizona State Parks. Legislators were shown a video of the cave in closed caucus meetings, and both houses passed the purchase bill in a single afternoon. Governor Rose Mofford signed it on April 27, 1988, and the state completed the purchase on September 16, 1988.

Development took more than ten years and cost over $28 million, with what the park calls extraordinary precautions to keep the cave in near-pristine condition. The upper caverns opened on November 5, 1999, and the lower caverns on November 11, 2003. The cave has an average temperature of 70°F and humidity of 99 percent.

The formations are the draw. The Throne Room holds Kubla Khan, a 58-foot column that is the tallest in Arizona, and one of the world's longest soda straw stalactites at 21 feet 3 inches. The Big Room has the world's most extensive formation of brushite moonmilk. A colony of cave myotis bats, about 1,000 on average, spends summers in the Big Room, so it closes to visitors from April 15 and reopens on October 15.

All tours are guided. The Rotunda/Throne Room tour runs year-round; the Big Room tour runs from October 15 to April 15. You cannot take anything into the cave, including bags, phones, cameras and water bottles, and lockers are provided. Photography is not allowed except on a monthly photo tour. If you have been in another cave or mine since 2005, don't bring the same clothes or shoes: staff will spray them to stop the spread of white-nose syndrome, a fungal disease that kills bats.

Above ground, the Foothills Loop (about 2.5 miles) and the Ocotillo Trail climb the hills with views of the San Pedro Valley, and the 4.2-mile Guindani Trail heads into the Whetstones. The park has a campground and cabins, and it is an International Dark Sky Park.