I've always wanted to explore an active volcano. So last year, I traveled to Bardarbunga in Iceland, the largest eruption in 200 years, that dumped more than 1.4 cubic kilometers of basaltic lava.
After circling the volcano in the helicopter for a while (where we could feel the blistering heat), we landed and explored the lava field by foot. It was mesmerizing to spend an hour in such close proximity to the volcanic activity.
My biggest regret: I got my friend's ice pick stuck in a square piece of lava when not removing it fast enough. I remember thinking "interesting, this looks like Thor's hammer and would be an awesome piece to keep." It took me a while but I wrestled the hammer loose from the lava and carried on. On the way home in the helicopter I told my buddy about it. His face dropped with sadness. His name was Thor :/