A whole world of sights exist in the Lava River Cave, Oregon’s largest continuous lava tube.
The cave is part of the Newberry National Volcanic Monument. It's roughly 5,211 feet in length and was formed during a volcanic explosion about 80,000 years ago. The source of the lava is believed to have been from the near Mokst Butte southeast entrance. It's part of the same volcanic flow that formed miles of lava flows underneath the Bend area.
Cavers can head in on self-guided explorations, which often take 1.5 hours to see the entire tube. Prepare to see fascinating subterranean sights and cave critters, but also be ready for the unique environment of the cave, with its cold temperatures and lack of light. The cave is usually around 42 degrees Fahrenheit (even in mid-summer) and the floor is uneven and sandy. Close-toed shoes are highly recommended.
The cave is open from May to September and closed during the winter months. Lanterns can be rented at the entrance for $5 until 4 p.m. A $5 per-vehicle charge is in effect May 1 through September 30.
Direction from Bend: Travel south on Highway 97 to Exit 151/Cottonwood Rd. Turn left and continue through the underpass following signs to Lava River Cave. The cave is about 1 mile down the road on the left.