Just outside Reykjavik, my husband and I happened upon an area called Seltun that was replete with geothermal activity - steaming vents, bubbling mud pots. The air was thick with sulfur that smelled like rotten eggs, and water and mud boiled in exposed pools, leaving behind interesting mineral deposits and formations.
When I first saw this mud pot I thought it looked like ice, which would make sense for Iceland in January. But these mud pots were actually boiling hot, and the holes in the top layer were caused by the very opposite of ice: hot water bubbling up and out of the pots.
Iceland is a country of amazing contrasts, in this case steaming hot mud on a cold winter's day.