While Arizona is famous for its ... Details: In the Santa Rita Mountains near Patagonia. fs.usda.gov. This milelong lava tube north of Flagstaff formed about 700,000 years ago.

Lava River Cave is located almost 20 miles northwest of downtown Flagstaff off of U.S. Route 180. Visiting is free. Although the cave is open year-round, roads may close in winter, particularly in ...