One of the attractions on the scenic road to Hana is Hana Lava Tube, also known as Ka'eleku Caverns. As the name implies, the cave was formed by flow of lava. The most interesting sight in the cave are very beautiful lava-stalactites that resemble dripping chocolate. They were formed already during the formation of the cave, probably when the hot lava was leaving the tube. As the patches of molten lava were dripping from the ceiling and cooled, the lava-stalactites were formed.
The whole lava tube is more than 2 miles long, but the part that is open to sightseeing is "only" 0.25 miles long. The cave is quite wide as well and its floor is almost horizontal, so it is easy to walk on. My father is supposedly claustrophobic, but had no problems there. You can visit this cave on a self guided tour, which costs 12$ per person. Not sure if I would recommend it though. I guess it depends if you are into caves or not...
Entrance to the cave:
Actually, for the most part the cave is quite tall and wide, and there is no need to get down on all your fours. But we did it anyways!
My parents in front of the wall of beautiful stalactites, also called "chocolate tongues":