Lake Yoa is the most famous, and second largest of the Lakes of Ounianga, a series of Lakes in Borkou-Ennedi-Tibesti Region basin of northeastern Chad. It is located in the Ounianga Kebir about 40km west of Ounianga Sarir. These lakes are remnants of a much larger lake which occupied this basin during the African Humid period which lasted from approximately 15,000 to 5,500 years before present.