The 16-km-wide Tengger caldera is a volcanic complex that dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes, each truncated by a caldera. Lava domes and pyroclastic cones occupy the flanks of the massif. This moon landscape is one of the coolest things you can see on this planet, preferably in the sunrise when the fog on the crater floor mixes up with the fresh rays of the sun.