Malawi sat on the eastern slave route, not the Atlantic one. The lake carried captives to Kilwa, and the trail that records it is on the Tentative List.
Malawi newest World Heritage property is a mountain inscribed for what it means, not for how it looks: a sacred landscape of the Yao, Manganja and Lhomwe.
The plateau above the old capital, where the colonial administration went to escape the heat. Forest, escarpment and long views, and no World Heritage listing.