Hiking to the Gateway to Hell on Hekla, Iceland
Apocalyptic tales of a great fire-and-brimstone volcano spread throughout medieval Europe, as pervasively as its ash clouds. Hekla erupts with little warning, spewing explosive projectile "bombs," blankets of cinders, and poisonous gases (making Eyjafjallajökull's eruptions in 2010 look like child's play). Erratic as Hekla is, once it gets going, the activity can last for years, altering the climate in continental Europe, and creating nuclear sunsets that scared the living daylights out of medieval folks, turning up in their literature, art, and religious writings. For the time being, the mountain is a nice place for a hike--particularly if you like endless views of a snowy volcanic landscape unencumbered by human habitations.