C79 Grotto

I thought back to the documentaries I'd seen at Discover, those volcanic areas where there was often a fountain of water that would erupt every few minutes.

"Isn't that geothermal? This water isn't hot either? " I asked.

The Daoist shook his head and said, "It might not be due to geothermal activities. There should be a very large underground river that goes straight to the sea