Castle Geyser—which erupts every 10-12 hours or so, is one of Yellowstone's many fascinating geothermal wonders. See more tonight during #YellowstoneLive, starting at 9PM ET/6 PM PT or get a chance at winning your own trip: https://on.natgeo.com/2vI5KnS pic.twitter.com/kZ7UNxeUS3

Castle Geyser—which erupts every 10-12 hours or so, is one of Yellowstone's many fascinating geothermal wonders. See more tonight during #YellowstoneLive, starting at 9PM ET/6 PM PT or get a chance at winning your own trip: https://on.natgeo.com/2vI5KnS  pic.twitter.com/kZ7UNxeUS3

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