The second largest of the world’s continents, Africa is bounded to the north by the Mediterranean Sea, to the west by the Atlantic Ocean, to the east by the Indian Ocean and the Red Sea, and to the south by the juncture between the Atlantic and the Indian oceans. Variously described by outsiders, as the "Dark Continent" or the "Cradle of Mankind", Africa is a continent immensely rich in mineral and natural resources that helped attract plunderers and explorers alike. Africa is also blessed with a rich variety of wildlife and biological resources, the preservation of which continues to be a challenge for conservationists from across the world. Africa is also home to some of the world’s poorest people and many of its constituent countries are still undergoing the process of nation building to achieve integration with the rest of the world.