It looks like a huge hole in the ground from up close. You can't see it in this picture, but at the bottom of the crater is a wing from a Cessna airplane. Our guide told us that a pair of commercial pilots flew into the crater "for a closer look" and were unable to fly out because of downdrafts. They flew in circles until they ran out of gas and crash landed. Amazingly enough they survived, and continued to fly for the unnamed airline.