The timing of past humid phases in the Sahara, the nature of the environment when the desert climate was ameliorated, and people who occupied it when it was green are poorly understood. Here we report the excavation of a shoreline deposit of the Chotts Megalake, a giant paleolake in the Southern Tunisia, that sheds light on these issues. The shoreline is located 4 km west of the town of Nefta and OSL dating shows it existed at 80-100 ka. The sedimentary deposits contain Aterian lithics indicative of archaic Homo sapiens occupation, found in association with an extensive assemblage of vertebrate remains that suggest a savanna environment at the time and a completely different geomorphological dynamic than the actual situation. Fractures and cut marks on the bones indicate either hunting and/or scavenging of carcasses by humans. The mollusc assemblage at Nefta differs from that of other Chotts Megalake shoreline deposits, being the only one that lacks Cerastoderma glaucum, a species found in brackish waters. In order to determine if the Nefta mollusc assemblage differed because the lake was fresh we collected fossil molluscs from numerous shoreline deposits, and from extant molluscs living in the freshwater springs found on the margins of the megalake. Carbon and oxygen isotope analysis show that the Nefta molluscs have an isotopic composition similar to the freshwater spring molluscs, but significantly different from those found in other shoreline deposits. Thus the Nefta deposit provides evidence of freshwater megalake in a humid Sahara during MIS5A with H. sapiens activities on the lake shoreline (lithic knapping, animal butchering....). The location of these new sites has provided a more understanding and more precise mapping of the extension of the northern margins of megalake.