For a long time it was relatively quiet around the world’s coldest volcano: Ol Doinyo Lengai is located in the Tanzanian part of the East African Rift Valley and produces a type of lava that is half as hot as ordinary lava with temperatures around 500 degrees Celsius. In 2008, a series of paroxysms filled the old crater and grew a new cone. Since then, the world’s coldest lava has been bubbling deep down in the new pit crater. Recent images show that the deep hole is constantly filling up. The crater floor is still inaccessible without technical aids, but slowly it rises to such an extent that one can see properly again from the crater rim. The tip of a hornito almost towers above the edge of the pit and lies approximately at the level of the more gently inclined crater rim. The video shows a crack in the hornito spraying sodium carbonate. Satellite photos confirm a weak thermal anomaly in the crater. It will be several years before the crater floor can be walked on again, unless the flow rate increases significantly.