South Ice Cave is a Forest Service recreational facility located on the southeast flanks of Newberry Crater. From the entrance through a large roof collapse the tube trends both north and south. The 50-m-long north passage ends in roof and wall collapse. The south passage extends more than 200 m over collapsed basalt blocks and ice to the collapse terminus.
Surface water seeps through the roof - the tube is dripping wet - and freezes. Ice glazes most of the passage, and icicles and ice stalagmites are common toward the end of the tube. Near the terminus, part of an aa flow is visible on the floor. South Ice Cave is a fairly large lava tube, and in places is more than 16 m wide and 6 m high. The tube formed in basalt erupted from one of the Newberry Caldera flank flows.