boiling mudpools in krafla caldera, iceland

active activity area blue boiling brown bubble caldera colorful danger earth energy environment erupting eruption exploding force fumarole gas geological geology geothermal geyser ground heat hot hydrocarbon iceland krafla landmark landscape lava magma microorganisms mountain mud muddy myvatn national natural nature old park pool power pressure scenic sky smell spring steam steaming sulfur thermal travel volcanic volcano vulcano water yellow