Jeff Vanuga / Ephydrid flies (Ephydra sp) that eat microscopic algae and survives during the winter in thermal pools. Biscut Basin, Yellowstone National Park, Wyoming, USA, January.

Nick Garbutt / American bison (Bison bison) female grazing near thermal pool, snow on ground. Biscuit Geyser Basin, Yellowstone National Park, USA. February 2019.

Kirkendall-Spring / Small frost covered trees in water with ice on, Biscuit Basin, Yellowstone National Park, Wyoming, USA, February 2014.

Kirkendall-Spring / Photographer on wooden walkway with steam rising from geothermal features, Biscuit Basin, Yellowstone National Park, Wyoming, USA, February 2014. MR.

Jeff Vanuga / American Bison / Buffalo (Bison bison) frosted with snow walking by water. Biscuit Basin, Yellowstone National Park, Wyoming, USA, January.

Kirkendall-Spring / Tourists on viewing platform along the Firehole River in winter, surrounded by frost-covered trees and snow, Biscuit Basin, Yellowstone National Park, Wyoming, USA. January, 2022.

Kirkendall-Spring / Walkway in fog, Biscuit Basin, Upper Geyser Basin, Yellowstone National Park, Wyoming, USA. January, 2022