Climb an active volcano.
I've been someplace no one can ever go. In 1997 I summited Ecuador's Tungurahua, an Andean peak not as storied as nearby Chimborazo or as monstrous as Argentina's Aconcagua. Unlike its more famous cordillera cousins, though, Tungurahua is a currently active volcano.
Making my way through the craggy, sulfurous plateau skirting the crater, I could smell, taste, and even hear it. This mountain was alive – or maybe it was that it wanted me dead. The unease I felt dogged me until I was safely home.
Tungurahua belched to life two years later, forcing a months-long evacuation. The fireworks began again in 2006 (and again in 2014), when the volcano coughed up molten rock fragments that destroyed several villages. The glacier I stood upon a decade ago, ice ax raised aloft in a goofy tableau, has been melted by the heat of the inner earth. There's an eerie, delicious pleasure in knowing I have looked down from a vantage point that no human in this geologic era will again experience.