The Lava has solidified (maybe a decade ago) but it still reminds me of how the lava was flowing. The ripples look like the lava was getting very viscous.
The lava flowed this far, but no further. The highway used to go through, but a lava flow 1983 destroyed the route. Now it's the start of an inland trail that (depending on the lava conditions) can take you to flowing lava.
It looks like bubbles formed just below the surface but the rocks solidified before they reached the surface. Years later, the surface of the bubbles broke.