Colossal Cave Mountain Park near Vail, Arizona offers cave tours, hiking and biking trails, horseback riding, camping, and picnicking across a 2,400-acre historic park featuring the crystal-filled Colossal Cave and the 120-year-old La Posta Quemada Ranch. Campsites are tucked among saguaro cacti and mesquite trees in Posta Quemada Canyon — 30 primitive sites across El Bosquecito and La Selvilla, both with water and restrooms. First-come first-served, $15/night. No electricity or RV hookups.

Kartchner Caverns State Park near Benson, Arizona protects one of the most remarkable living cave systems in the world — 2.4 miles of passages discovered in 1974 and kept secret for 14 years to ensure its preservation, featuring Kubla Khan the tallest column in Arizona at 58 feet, a 21-foot soda straw stalactite, and a cave environment maintained at 68°F and 99% humidity year-round through a system of airlocks and misting chambers.

Lava River Cave northwest of Flagstaff is Arizona's longest accessible lava tube — a mile-long underground corridor formed 700,000 years ago when molten rock drained from a solidified outer shell, leaving a dark, cathedral-quiet passage through the Coconino National Forest ponderosa pine country at 7,684 feet.

Robbers Roost Trail near Sedona leads to a historic outlaw hideout cave in the red rock country of the Coconino National Forest — a rocky trail through classic Arizona high desert to a cave with framed views of Sedona's red rock cliffs, a dozen or more deer grazing in the canyon below, and dispersed camping available along the adjacent FR 258 Buckboard Road for those looking to stay.

Explore the Tabernacle Hill Lava Tubes in Utah, a captivating natural wonder located near Leeds. This unique geological formation offers adventure seekers a chance to hike, explore underground lava tubes, and take in scenic desert landscapes. Ideal for outdoor enthusiasts, photographers, and campers, the lava tubes are a must-see for those seeking an off-the-beaten-path experience in Southern Utah.