Featured image from Wikimedia Commons | May 30, 2017

The Berca Mud Volcanoes. Berca, Buzau County, Romania

https://upload.wikimedia.org/wikipedia/commons/2/2f/Volcanes_de_lodo%2C_Buzau%2C_Ruman%C3%ADa%2C_2016-05-29%2C_DD_43.jpg