Join ExplOregon on Saturday, May 12th as we head to Bend, OR to explore the Lava River Cave! Lava River Cave offers self-guided exploration of a mile-long lava tube. It takes approximately 1.5 hours to tour the entire cave.Lava River Cave is estimated to have been formed around 80,000 years ago from an eruption that flowed as far north as Redmond, Oregon.