Biggest Cave | Scariest Predator | Driest Desert | Hottest Geysers | Largest Glacier | Highest Peak | Tallest Tree | Highest Biodiversity | Largest Primate | Most Active Volcano | Strangest Rock Formation | Biggest Bear | Largest Crater | Farthest Migrator | Tallest Waterfall
What Cataclysmic meteorite crashes and volcanic eruptions leave these gaping pits behind. More than 160 known craters come from the impact of meteorites, with South Africa's Vredefort Dome the largest at 118 miles across. Others appear when lava (sometimes more than 20 cubic miles' worth) explodes from a composite volcano, causing the summit to collapse on itself and forming immense craters (called calderas) with steep, symmetrical sides.
Where Ngorongoro Crater, Tanzania. Take a guided "walking safari" through the planet's biggest unbroken volcanic caldera–102 square miles and 200 feet deep–where dense populations of wildebeest, zebras, hippos, rhinos, and gazelles graze. ngorongorocrater.org