Its Indian Ocean coastline and the major islands of Mafia, Pemba and Zanzibar are protected by coral reefs. The mainland is dominated by a large central plateau, one covered with grasslands, plains and rolling hills. The Serengeti plain is a large geographical region that spans some 30,000 km2 (12,000 sq mi).
Tanzania is mountainous in the far-northeast, where Mount Kilimanjaro, Africa's highest peak is located. That mountain stands at 19,340 ft. (5,895 m) tall. The Rubeho Mountains are much lower in elevation, and a compact group of connected peaks.
The Ngorongoro Crater is the world's largest intact caldera forming a spectacular bowl of about 265 sq km with sides up to 600m (1,960 ft) deep.
The country is bordered by some of Africa's largest lakes, including Lake Nyasa (Lake Malawi), Lake Victoria (Africa's largest lake), and Lake Tanganyika (Africa's deepest lake).
The Rufiji river is the largest in Tanzania, draining most of the southern part of the country. Formed by the confluence of the Kilombero and the Luwegu rivers, it flows for about 175 miles northeast and east to enter the Indian Ocean (Tanzania's lowest point). Its major tributary is the Great Ruaha.