Africa has 54 sovereign countries—the most on any continent—and is the second largest continent in terms of both land area and population. Africa is bounded by the Mediterranean Sea to the north, by the Atlantic Ocean to the west, by the Red Sea to the northeast, and by the Indian Ocean to the southeast. Africa is a vast continent spanning over 8,000km (5,000 mi) north to south and 7,500km (4,800 mi) east to west (not including islands) and contains a wide array of peoples, skin colours, religions, and cultures. Africa contains the world's longest river—the 6,650km long (4,100 mi) Nile River running from Burundi to Egypt—while the Congo River in the DRC is the second largest in terms of discharge as well as the deepest with a depth of over 230m (750 ft) in some spots.Tanzania's Mount Kilimanjaro is the world's tallest free-standing mountain at 5,890m (19,340 ft). Djibouti's Lake Assal is the second lowest point on Earth, the saltiest lake outside Antarctica, and one of the hottest places on Earth.