Some of my favorite waterfalls are volcanic, especially in winter while on an adventure.  It’s a great way to start or end the day; they also are life saving in icy weather.  Several times I can recall being stuck in blizzards, with hot spring nearby, once in the Rocky Mountains, the other was in Nagano Jigokudani “Hell’s Valley” best known for snow monkeys.  These two times was with a film crew; we sure did enjoy the natural warmth.   It’s handy to carry a shovel with you just in case; you need to make your custom bath.  Today we spent hrs refreshing ourselves in the natural hot springs,  mind & body.