Kilauea, Hawai'i
This is definitely not your parent's version of hell. Fire and brimstone (though, Hawai'i has no brimstone) never looked so beautiful. Lava and water in all their power.
Kilauea has been erupting since 1983; constantly adding new land to the big island of Hawai'i. An awesome sight. Luckily, on my second visit to Hawai'i, we flew over the volcano and saw the lava. Unfortunately, it was in the daytime so the full effect was not experienced. However, on my third visit (you'd think I loved Hawai'i or something... oh, that's right; I do!) some friends and I were able to see it at night and get as close as five feet from some of the active flows. Now that was spectacular!
It's no wonder there is the Hawaiian mythos of Pele as the Goddess of Fire; just don't piss her off.