Derrick’s Cave is estimated to be 1,200 feet (370 m) long, perhaps Oregon’s third-longest lava tube cave.  Derrick Cave was named for H.E. Derrick, a pioneer rancher in the Devils Garden area. Derrick Cave developed just south of the main vent for the Devils Garden Flows and was the route of most of the lava which spread south from the vent.  Additional lava from the vent went to the north and west via a large gutter system (open lava river channel).

Over a short distance one can see the vent, an open lava river channel, short roofed-over channel sections, and a well-developed lava tube.  The northeast end of the cave is about 600 feet long and is characterized by thin roofs, multiple skylights, short multiple levels, and wide sandy floored passages.  The southwest end is about 1200 feet long and is relatively narrow, deep and thick roofed.

In the 1960s, Derrick Cave was a designated nuclear fallout shelter with supplies of food and water.