Jeff Foott / Geyser spouting, Old Faithful, Yellowstone National Park, Wyoming

Jeff Vanuga / Old Faithful Geyser erupting at -30 Celsius in winter. Upper Geyser Basin, Yellowstone National Park, Wyoming, USA, January 2015.

Floris van Breugel / A skier glides past an erupting geyser in the Old Faithful geyser basin in Yellowstone National Park. The cold temperatures in the winter cause the geysers to release more steam than usual making the...

Peter Cairns / Castle Geyser erupting at dawn, Old Faithful geothermal area, Yelowstone National Park, Wyoming, USA, September 2008

Pete Cairns / Morning glory pool, Old Faithful geyser, Yellowstone NP, Wyoming, USA

Sumio Harada / Old Faithful Geyser spouting, Yellowstone National Park, Wyoming

Ingo Arndt / Old Faithful geyser errupting, Yellowstone National Park, Wyoming, USA

Kirkendall-Spring / Tourists watching Old Faithful Geyser in Upper Geyser Basin, Yellowstone National Park, Wyoming, USA. September 2015.

Paul Hobson / Old faithful geyser landscape, Yellowstone National Park, Wyoming, USA, February.

Paul Hobson / Landscape of Old faithful geyser, Yellowstone, Wyoming, USA, February.

Peter Cairns / Tourist using iPad to photograph Old Faithful geyser, Yellowstone National Park, Wyoming, USA, October 2012.

Kirkendall-Spring / Bombardier snow coaches lined up in front of Old Faithful Snow Lodge, Yellowstone National Park, Wyoming, USA, February 2014.