Mainland Tanzania is where the Great Migration actually spends most of its year — the Serengeti's endless plains anchor one of the largest concentrations of wildlife left on the planet, and the Ngorongoro Crater delivers dense, near-guaranteed game viewing inside a single collapsed volcanic caldera regardless of season. Add Tarangire's elephant herds and baobab-studded landscapes and you have a Northern Circuit that works whether you've got four days or two weeks, built around Arusha as the safari gateway town where most trips start and end.
Kilimanjaro rises just east of Arusha as Africa's highest peak and a genuine trekking objective in its own right, drawing climbers on routes that need no technical experience, just fitness and the right season. Dar es Salaam, the country's commercial capital on the Indian Ocean coast, adds a practical city base for business travel and a jumping-off point for the coast — and for travelers who want to pair the safari with beach time, Zanzibar sits just a short flight or ferry away as a natural extension rather than a separate trip.