Ok, time for plan B - go to the local hardware store, buy an umbrella, checkout of the inn, and do the loop drive again. We stopped at a few places we missed the day before.
We figured we would give Thunder Hole another shot since the "thunder" level is highly dependent on the tide level and wave action.
This time it was living up to its name! About 1 in 5 waves would be timed just right and the compressed air would be released with a truly thunderous boom. You could feel the concussion in the ground and your chest.