Olympus Mons is Mars's tallest volcano, reaching 21.9 km above sea level. It is 600 km wide and covers an area of 300,000 km². The volcano has six nested calderas forming a 60x80 km depression. Its average slope is only 5%, with steepest points near the middle
Volcano is a vent allowing lava and gases to escape from magma chamber. Most volcanoes found where tectonic plates diverge or converge. Volcanoes can form at plate boundaries, hotspots, or continental rifts
Krakatoa is a caldera in Sunda Strait between Java and Sumatra. Four volcanic islands form Krakatoa archipelago: Lang, Verlaten, Rakata, and Anak Krakatau. Island was known as "The Fire Mountain" during Sailendra dynasty
Hekla is a 1,491m high stratovolcano in south Iceland. Located on 40km long volcanic ridge with Heklugjá fissure. Contains unusual magma reservoir with depth over 10km. Produces calc-alkaline lavas with SiO2 content over 54%
Located on Ross Island, Antarctica, at 3,792 metres elevation. Second-highest volcano in Antarctica after Mount Sidley. Contains persistent phonolitic lava lake since early 1970s. Features numerous ice fumaroles and dark caves
Olympus Mons is the largest volcano in the solar system. Rises 16 miles above surrounding plains, spanning 374 miles. Contains 100 times volume of Earth's Mauna Loa. Has average slope of only 5 percent