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.

This mile-long lava tube cave was formed roughly 700,000 years ago by molten rock that erupted from a volcanic vent in nearby Hart Prairie. The top, sides and bottom of the flow cooled and solidified first, after which the insides of the lava river continued to flow emptying out the present cave.

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.