Telegeography has just launched a free online submarine cable map. Cables shown include international and US domestic submarine cables with a maximum upgradeable capacity of at least 5 Gbps. It includes all of the recent cables touching the African continent.
The detailed map can be viewed here.
Another widely-viewed map of African submarine cables is the one maintained by Steve Song here.
Telegeography also publishes a list detailing 233 currently active and planned undersea cable systems, their status (operational or planned), and the cities and countries in which they land. This is available here.