Kosi Bay is a series of four interlinked lakes in the Maputaland area of KwaZulu-Natal, South Africa.

The lakes form part of the iSimangaliso Wetland Park, a UNESCO World Heritage Site.

Bird species in the area include the palm-nut vulture, Pel's fishing owl, white-backed night-heron, and kingfishers.

Duiker, hippopotamus, crocodiles and bull sharks are also present, and loggerhead and endangered leatherback sea turtles lay their eggs on the beach.

When Britain colonised South Africa, Kosi Bay was annexed to Natal, while Maputo was annexed to Mozambique.Several tourism operators offer experiences in the area, including guided or self-sustained hikes along trails that offer the opportunity to experience the ecosystem up close, walking across sand dunes, along pristine beaches and through coastal forest.