Nestled deep in the heart of the Ngorongoro Conservation Area in Tanzania’s legendary Serengeti lays the Ngorongoro Crater–a large, unbroken caldera that formed when a giant volcano exploded and collapsed on itself a few million years ago.

Today, the 2,000-foot-deep, 1,000-square-mile Ngorongoro Crater boasts a richness and diversity of wildlife that lives up to its big bang start. Home to an estimated 25,000 animals, the crater boasts not only the Big Five (rhinos, lions, leopards, elephants, and buffalo) but zebras, gazelles, wildebeests, and more.

And yet the crater, because of its geographic enclosure, is also home to interesting genetic experiments. Some animals–most notably lions–face serious problems as the result of generations of inbreeding, and when migrating male lions try to dip into the local gene pool they are easily bested by the unusually large lions that have benefited from generations of abundant food.

Archaeologists estimate that hominids have also occupied the crater since its inception a few million years ago, with pastoral farmers replacing hunter-gatherers a few thousand years ago. The Maasai have roamed the crater since the 1800s, and still do, in a situation unique in Tanzania that allows for the human occupation of a protected conservation area. Since 1979, the conservation area has also been declared a UNESCO World Heritage Site.

For those who come to Tanzania to climb Mt. Kilimanjaro, we at Embark are compelled to at least offer an extended stay post-climb to safari through the region, with the Ngorongoro Crater being the ultimate highlight. In the summertime, the area is witness to one of the largest migrations in the world as millions of wildebeest, 470,000 gazelles, and 260,000 zebra pass through the plains of the reserve, to name just a few. It should be noted that cheetahs, which are common in the reserve, have grown scarce within the crater itself, and that the African wild dog has all but disappeared from the crater and throughout the country, too.