I took this picture from the raft as we pulled up to the beach at Redwall Cavern Grand Canyon, USA. Very hard to tell the scale of a cavern with a picture, but you see the boulder in the bottom right corner is the size of two full size Dodge trucks

Redwall Cavern is one of the hidden marvels tucked within the Grand Canyon, located at river mile 33 along the Colorado River. It’s a massive natural amphitheater carved into the Redwall Limestone a towering, rust colored rock layer that forms steep, vertical cliffs throughout the canyon.