We spend most of this day on a black sand beach that is striking as the beach is beautiful and has caves on either side. The water is crystal clear. The sand is really hot, and we have to race back and forth to the water. I have interaction with a local on Instagram who is trying to convince me that the black sands and pebbles are not volcanic origin, but are from coal dumped when the railroad was built. What do you think? All my research points to volcanic output, and it does not seem logical or feasible that the coal would reach far out to sea, or color the rocks in the caves, which are quite substantial, black as well.