Boyd Cave is in many ways similar to Skeleton Cave. It is a well preserved lava tube, little collapsed, and exhibits flow structures in pahoehoe of the walls, ceiling, and floor. Some of the tube is spalled and sand is draining into the tube through roof fractures. Tube cross sections are typically asymmetrical in meander bends. Unlike Skeleton Cave, Boyd Cave roof is very thin, probably less than I m thick in some places. Small feeder tubes are visible at several stations. Most feeders extend from the main passage a few meters, or less, and are plugged.
Entrance to the tube is through a 3 m diameter skylight, via a Forest Service stairway. The tube extends about 25 m upslope and is blocked by sand; however, the tube probably continues upslope beyond the blockage. Sand covers the flow downslope in the tube about 75 m, evidently having washed down from the skylight. A prominent pahoehoe flow line is on the east wall about 1.5 m above the floor. The flow line continues down tube and is usually visible on both walls, although it may be better developed on one wall than the other.
To Get there, take Highway 97 South through Bend, turn left on China Hat Road. Go straight for exactly 9 miles. Turn left at mile 9 onto the trail at FS242. You will know it has been 9 miles if you see a cattle guard and the road becomes unpaved just a few feet ahead. The small park sign will say .5 miles to Boyd Cave, continue on till a round about and look for the stair case.