Many of the tubes had very large holes created when the ceiling fell. These holes we used to climb down into the caves.
Inside the cave, the lava tube became more visible. Many of the caves were not this large, however. Many times we had to crawl low, or move slowly around large rock. Also, it was so dark, flashlights were needed.
Most of the caves we entered, we came out at a different spot. The tube had formed a tunnel.
The hole that we came out of the cave was often much smaller than the hole in which we entered the cave.