The Nile is a major north-flowing river in northeastern Africa. It is commonly regarded as the longest river in the world, though other conflicting sources cite a 2007 study that gave the title to the Amazon River in South America. The Nile, which is 6,853 km (4,258 miles) long, is an "international" river as its drainage basin covers eleven countries, namely, Tanzania, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea, South Sudan, Sudan and Egypt. In particular, the Nile is the primary water source of Egypt and Sudan.
Africa is the world's second-largest and second-most-populous continent (the first being Asia). At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20.4% of its total land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, both the Suez Canal and the Red Sea along the Sinai Peninsula to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognized sovereign states (countries), nine territories and two de facto independent states with limited or no recognition.
Africa has the most independent countries. There are indeed 53 recognized countries, one disputed territory being Western Sahara and one country, Somaliland, that is not recognized. The figure 53 is still higher than the second continent by population, Europe. The next in the list is Asia, with 48 countries.
The Vaal River is the largest tributary of the Orange River in South Africa. The river has its source near Breyten in Mpumalanga province, east of Johannesburg and about 30 kilometers (19 mi) north of Ermelo and only about 240 kilometers (150 mi) from the Indian Ocean. It then flows westwards to its conjunction with the Orange River southwest of Kimberley in the Northern Cape. It is 1,120 kilometres (700 mi) long, and forms the border between Mpumalanga, Gauteng and North West Province on its north bank, and the Free State on its south.