Describes the architecture of the Africa Optical Network (Africa ONE) that will encircle the entire continent of Africa with an undersea fiber optic ring network. Using a combination of wavelength-division multiplexing (WDM) and synchronous digital hierarchy (SDH) multiplex and cross-connect equipment, Africa ONE brings together a unique blend of technology to achieve network robustness. The article traces the need for this regional network and how it fits into the global undersea communications network. Also the authors describe the network elements that make up the transmission topology, the methodology used for interconnecting each African country to this network, protection and restoration of the network, and the network management system. Africa-ONE is a 40,000 km trunk and branch network that is planned to be ready for service in 1999. The present article presents the architecture of the undersea portion of the Africa-ONE project.