Tanzania's Northern Circuit is the most complete wildlife itinerary on the African continent, and seven days is exactly the right amount of time to do it properly. This group joining safari moves through four distinct ecosystems in sequence, each one building on the last. It opens in the baobab-studded woodlands of Tarangire National Park, where some of the largest elephant herds in East Africa gather around the Tarangire River during the dry season. From there the route drops to Lake Manyara, a compact but extraordinarily productive park where the alkaline lake attracts hundreds of flamingos and the groundwater forest harbours the tree-climbing lions that Tanzania is famous for. Two nights follow in the central Serengeti at Osinon Tented Camp, placing you deep inside the park during the hours when predator activity peaks and the plains stretch uninterrupted to every horizon. The circuit concludes with the most dramatic single experience on offer anywhere in Africa  a descent into the Ngorongoro Crater, a 20-kilometre-wide volcanic caldera that functions as a natural enclosure for a permanently resident population of all Big Five species, including one of Tanzania's last viable black rhino populations.