It can be, like on a roller coaster. So yes, in that sense, the bounding, bucking, bouncing, and bumping all over the bed of that truck was fun. It must have been, because we were laughing our butts off the whole time.
Reaching the beach after the ride still required climbing over and down the steep sides of the volcanic crater, so we were more than ready to just lay out and relax on the sand for a while.
We are also happy to report that our driver was kind enough to take it a little easier on us on the way back.
Afterwards we learned that what we had done is not allowed. The Department of Hawaiian Home Lands has restricted vehicular traffic through the grassland, so we are not sure if the off-road entrepreneurs are always operating, but our guess would be that they usually are.