Italian explorer who discovered Lake Kyoga (Kyoga Lake) (in Uganda) and investigated the Upper (southern) Nile River system.

Lacking a formal education, Piaggia was an acute observer who collected a wealth of information about the geography, natural history, and ethnology of northeastern Africa. He made the first study of the then-unknown Zande tribes in the southern Sudan and northeastern Democratic Republic of the Congo.

Piaggia first entered the interior of Africa in 1856 to collect specimens of rare animals in the Egyptian Sudan. In 1860–61 he again accompanied naturalists to the Egyptian Sudan, reaching the basin of the Gazelle River (Baḥr al-Ghazāl) and the borders of the Zande nation. Intrigued by the Zande peoples, he undertook an expedition among them (1863–65), returning with a mass of ethnographic data. Later (1871) he explored the Ethiopian highlands and circumnavigated Lake Tana. On another expedition to explore the Upper Nile (1875), he searched for a river passage between the Nile and the great lakes of East Africa; during this journey he discovered Lake Kyoga (1876). He died while on an exploration of the Blue Nile.