Holy CRAP. Look at this thing. I thought that it was Photoshopped at first, but Gizmodo vouches for its authenticity and they're usually pretty reliable. Apparently this happened a couple years ago too, according to National Geographic.
Here's the article.
The Gates of Hell Just Opened In Guatemala
Here's the one from today (via Gizmodo):
And here's the one from 2007 (via National Geographic):