Tourists visit the interior of Cuexcomate volcano, at La Libertad town, in the city of Puebla, capital of Puebla state, Mexico, on Aug. 18, 2015. According to local press, the Cuexcomate volcano, whose name comes from the Nahuatl word "cuexcomatl" which means "clay pot" or "place to keep", is known as the world's smallest volcano. In fact, it is not a volcano but a formation caused hundreds of years ago by a flow of hydrogen sulphide water a result of an eruption of the Popocatepetl volcano. Cuexcomate has a height of 13 meters, a diameter ranging from 8 meters in its crater up to 23 meters on the outside of its base and is located 2,150 meters above sea level.(Xinhua/Carlos Pacheco/NOTIMEX)