the west african coast is the western most region of Africa. the United Nations definition of western africa includes 16 countries over an area of 5 million square km. (en.wikipedia.org/wiki/West_Africa) I believe the 15th century Portugse definintion included the coast which extended to the Cape of Good Hope discovered by Bartolomeu Dias in May of 1488 having passed it without seeing land whille searching for a route to India on the reurn journey to Portugal. (en.wikipedia.org/wiki/Bartolomeu_Dias).
the Portugese exploration consisted of coastal areas only during this period. The west african coast having very few natural harbors for anchorage. The Niger river and The Gambia are the two major rivers in west africa neither of which provided egress to the interior due to large aluval plains at the mouths of the rivers. Small islands were used for bases for the Portugese ships such as the Cape Verde Islands.
The coastal regionknown as the Ivory and Gold coasts are lined with mangrove swamps, sandy beaches and dense vegitation further inland are rain forested plains and mountious plateau. there are two seasons, the rainy season from May to November and a dry season from December to May. (en.wikipedia.org)
Another deterant to european exploration to the african coast was mosquitoes, malaria, dengue and yellow fever. Benin was called "the white man's grave". To slavers of that era west africa was three seperate zones, surf, brown sand, and jungle beyond. (Black Cargos, Mannix, pg. 13)
The peoples of west africa were called Negroids. They were devide into two groups, "true negros in the northwest and Bantu in the south and east. The distinction is more due to language then racial. Both peoples have dark skins, wooly hair, and broad noses. they were depicted as of average height by early europeans which means approximitly the same height as temselves. The majority of slaves shipped to the new world were Negroids because the great centers of the atlantic trade were located from Senegal to Angola where the Negroids were predominate. (Black Cargos, Manix, pg. 8)
The area due to climate, insects, dense vegitation, and lack of natural anchorages would make this area seem very inhospitable to the Portugese. They would have to leave the safety of their ships which would be well of shore, to explore, search for slaves, or barter with the area inhabitants.