Geoff Mackley has a thirst for adventure.
The scientist says, "Mother Nature puts on the most amazing shows."
That's one reason he climbed down into an active volcano.
He told the Today Show, "there are very few places you can go, things you can do where you can really say wow!"
Asked if he was a little bit crazy Mackley said, "no, not crazy, I've been taking calculated risks for a long, long time."
Watch the Today Show interview below, or click here: http://today.msnbc.msn.com/