Nero's exploration of the Nile

[3] Accounts are found in Seneca the Younger's Naturales quaestiones, VI.8.3 and Pliny the Elder's Natural History, VI.XXXV, p. 181-187: The Roman legionaries navigating the Nile from southern Egypt initially reached the city of Meroe and later moved to the Sudd, where they had difficulties going further.

From Meroe the Roman party travelled 600 miles up the White Nile, until they reached the swamp-like Sudd in what is now southern Sudan, a fetid wetland filled with ferns, papyrus reeds and thick mats of rotting vegetation.

Seneca wrote De Nubibus, in the book Naturales Quaestiones, that gave details about a Neronian expedition to the caput mundi investigandum (to explore the top of the world) in 61/62 AD.

Indeed, Vantini wrote in the magazine Nigrizia, in 1996, that the legionaries completed a journey of exploration of more than 5,000 km from Meroe to Uganda: a remarkable achievement done using small boats in order to bypass the Sudd, a huge swamp full of dangerous Nile crocodiles.

Historian David Braund wrote, in 2015, that Nero's expedition to the Nile's sources probably opened a new route toward the Indian Ocean, bypassing the dangers of piracy in the Red Sea area while allowing future Roman commerce toward India and Azania.

Indeed, Diogene, a Roman merchant who lived between 70 and 130 AD, returning from one of his voyages, sailed along the Sinus Arabicus (the Red Sea) and, after having touched Adulis and Rhapta (near the border between Tanzania and Mozambique), he marched into the interior of the continent, up to two large lakes behind which rose the snow-capped mountains from where he thought the Nile was born.

[9] The Romano-Phoenician Marinus of Tyre also told the story of Diogene's journey, as did Claudius Ptolemy, who attested that in the center of the African continent there were certainly those large lakes fed by the "Mountains of the Moon" from which the Nile emerged.