In 66 AD, Emperor Nero dispatched a Roman expedition into the unknown reaches of northern Europe, beyond the Rhine and into the Baltic. This episode explores the likely route and purpose of this daring journey, which may have reached the Gulf of Finland and even the Lena River. Drawing on Pliny the Elder, Tacitus, and archaeological finds, we examine whether Nero sought amber, new trade routes, or simply imperial glory. The expedition's leader, possibly a Batavian auxiliary commander, faced harsh climates and hostile tribes. We also discuss the political context: Nero's need for a triumph in the north after the Parthian settlement and before the Jewish revolt. The episode raises questions about Roman knowledge of the Arctic and the fate of this forgotten mission. Keywords: Nero, Roman exploration, Baltic, amber, Lena River, Batavi, Pliny the Elder, Tacitus, Vistula, Fenni, Aesti, Sarmatians, Samland Peninsula, 66 AD, imperial politics, Prefect of the Praetorian Guard, diplomatic mission.