Fortuna Bay () is a bay long and wide. Its entrance is defined by Cape Best on the west and Robertson Point to the east, near Atherton Peak on the north coast of South Georgia. It was named after the Fortuna, one of the ships of the Norwegian–Argentine whaling expedition under C.A. Larsen which participated in establishing the first permanent whaling station at Grytviken, South Georgia, in 1904–05. The Second German Antarctic Expedition (SGAE) under Wilhelm Filchner explored Fortuna Bay in 1911–12. Discovery Investigations (DI) personnel charted the area during their 1929–30 expedition.
