'Gateway to Hell': Sinkholes Open Across Earth - Sinkho...
'Gateway to Hell': Sinkholes Open Across Earth
'Gateway to Hell': Sinkholes Open Across Earth,
NBC News,
A look at some of the most astonishing sinkholes which have turned up around the world.
http://www.nbcnews.com/news/photo/gateway-hell-sinkholes-open-across-earth-n247071