Kartchner Caverns' Big Room Reopens October 15, Once the Bats Are Gone
Kartchner Caverns reopens its Big Room tour October 15, 2026 through April 15: tour lengths, ticket prices, why bats close it, Bat Fest and I-10 work.
Nine miles south of Benson, the half of the cave a bat colony keeps to itself all summer goes back on the tour schedule for six months, with Bat Fest in the Discovery Center on Saturday, October 24.
Every April 15, the cave crew at Kartchner Caverns State Park closes all the doors to the Big Room, turns out the lights and pulls the plugs, so nothing switches on while a colony of cave bats raises its young in the dark. On October 15 the room opens again, and for the next six months the deeper of the park's two standard tours is back on the schedule — at 70 degrees and 99 percent humidity, whatever the weather is doing above it.
- Oct 15 – Apr 15
- Big Room tour season
- About 1,500
- Cave bats that spend part of the year in the cave
- 70°F / 99%
- Cave temperature and humidity, year-round
- 58 feet
- Kubla Khan, the tallest column in Arizona
Why Half the Cave Belongs to Bats All Summer
The tenants are Myotis velifer, the cave myotis, and about 1,500 of them use part of the cave for part of the year. Through the summer the Big Room is a nursery: the bats give birth there, raise their pups and teach them to fly, echolocate and hunt. Staff do not go back in until late September, after the colony has left. Nobody knows for certain where it winters; rangers suspect caves high in the Huachuca Mountains, about 40 miles away, where a hibernating colony of the same species was found at roughly 8,000 feet.
The other half of the cave, the Rotunda and Throne Room, stays open all year. Bats roosted there too — thousands of years ago, and that tour passes 45,000-year-old bat guano along the way.
Which Kartchner Caverns Tour Should You Book?
The Big Room tour covers half a mile in about an hour and 45 minutes, one hour of it underground. Its distinctions are mineral: the world's most extensive formation of brushite moonmilk, and the first reported occurrence of the formations known as turnip shields. Tickets are $30 for ages 14 and up and $15 for ages 7 to 13. Children under 7 are not admitted to this tour.
The Rotunda/Throne Room tour is also half a mile, takes about an hour and a half, and spends 50 minutes underground. It holds the headline formations: Kubla Khan, a 58-foot column that is the tallest and most massive in Arizona, and a 21-foot-3-inch soda straw stalactite that ranks among the longest in the world, plus the discoverers' original trail. Prices match the Big Room, with a $5 ticket for children under 7. The $50 Helmet & Headlamp tour, for ages 10 and up, runs on Saturdays other than the third of the month and moves into the Big Room from October through April.
A Cave Kept Secret for Four Years
In November 1974, Gary Tenen and Randy Tufts were exploring limestone hills at the base of the Whetstone Mountains when they found a narrow crack at the bottom of a sinkhole with warm, moist air flowing out of it. They kept the cave to themselves until February 1978, when they told the landowners, James and Lois Kartchner. Its existence became public in 1988, when its purchase was approved as a state park, and the park was dedicated on November 5, 1999. The Discovery Center now displays original 86,000-year-old sloth bones and a 36,000-year-old horse skull.
Before You Drive Down
Book ahead. Every tour is guided, the park recommends reserving as far in advance as possible, and walk-up tickets may not be available on a given day. Arrive at least 30 minutes before your tour time, or 15 minutes for an 8 a.m. start; a late arrival can forfeit the slot. Nothing goes into the cave with you — no phones, cameras, bags or water bottles — and photography is not allowed, so plan on a locker. Shoes or clothing worn in any other cave or mine since 2005 should stay home; the park otherwise sprays footwear at a decontamination station to keep white-nose syndrome away from the bats.
A cave tour reservation waives the park entrance fee, which is otherwise $10 for a single-occupant vehicle or $20 for two to four people. The café is closed until further notice, so pack lunch for after the tour; a new gift shop, Caverns Sky, opens October 15.
Allow for the road, too: the park warns that Interstate 10 construction may slow weekday traffic. The Arizona Department of Transportation's Amole Interchange and Union Pacific Railroad bridge rehabilitation, at mileposts 292 to 293 near Benson, had narrowed traffic to a single lane with a 55 mph limit and a 16-foot width restriction, with completion extended to fall 2026. Arizona does not observe daylight saving time, so the clock on your booking does not shift in November.
Bat Fest on Saturday, October 24
The bats are gone by late October, so the Discovery Center brings some back. Bat Fest runs from 9 a.m. to 4 p.m. on Saturday, October 24, 2026, with live bat ambassadors, arts and crafts, book readings, costume contests and presentations from local bat experts. Partners listed include the Arizona-Sonora Desert Museum, Bat Conservation International, Chiricahua National Monument and the U.S. Forest Service. It pairs naturally with a Big Room tour the same day; the park's event listing names no separate fest admission, so a visit without a cave tour reservation is the $10 or $20 entrance fee above. The park is also an International Dark Sky Park: its October 10 star party was canceled for weather, and the next is November 14, from 1 to 9 p.m.
From Tucson's Southeast Side, It Is an I-10 Morning
The route is Interstate 10 east to Benson, then nine miles south on State Route 90 to 2980 S. Highway 90. That makes it closest to Tucson's southeast side — Rita Ranch, Vail and Corona de Tucson — where an 8 a.m. Big Room slot and a lunch back home is a realistic Saturday. The 60-site campground and the park's cabins sit at the foot of the Whetstones for anyone who would rather pair a late tour with a night under a dark sky.
Quick plan: book the Big Room for any day from October 15 on, online or at (877) MY-PARKS, option 2 (8 a.m. to 4:30 p.m., seven days a week). Leave phones and water in a locker, bring a lunch, and add Bat Fest on October 24 if you want to see the bats you just missed. The Big Room closes again on April 15, 2027.
Sources
Arizona State Parks & Trails — "Cave Tour Information | Kartchner Caverns State Park" — azstateparks.com/kartchner/cave-tours/tours — accessed October 11, 2026.
Arizona State Parks & Trails — "Kartchner Caverns State Park" (park alerts, hours, entrance fees, address, events) — azstateparks.com/kartchner — accessed October 11, 2026.
Arizona State Parks & Trails — "Yearly Return of the Bats" — azstateparks.com/kartchner/cave-tours/yearly-return-of-the-bats — accessed October 11, 2026.
Arizona State Parks & Trails — "Living Cave Information" — azstateparks.com/kartchner/cave-tours/cave-information — accessed October 11, 2026.
Arizona State Parks & Trails — "Kartchner Caverns Cave History" — azstateparks.com/kartchner/explore/park-history — accessed October 11, 2026.
Arizona State Parks & Trails — "Facility Information" — azstateparks.com/kartchner/explore/facility-information — accessed October 11, 2026.
Arizona State Parks & Trails — "Bat Fest" — azstateparks.com/kartchner/events/bat-fest — accessed October 11, 2026.
KVOA — "Drivers face more I-10 bridge delays in Benson" (February 11, 2026) — kvoa.com/news/cochisecounty/drivers-face-more-i-10-bridge-delays-in-benson/article_5eaeea6f-bd89-4097-a0e6-70e0c70afb9e.html — accessed October 11, 2026.
All details current as of October 11, 2026; tour schedules, prices and road conditions change, so confirm with the park before you go. This post is for informational purposes only and is not an offer to sell or a solicitation of an offer to purchase real estate. Kyle Berglund and Tierra Antigua Realty fully support and comply with the Fair Housing Act and the Equal Opportunity Act.
Earlier coverage
- The Cave Room That Closes Every Year for Bat Season — April 28, 2026
Topics
- Things to Do
- Kartchner Caverns
- Benson
- Arizona State Parks
- Caves
- Bat Fest
- Day Trips