Erythropotamos is one of the main tributaries of the Evros river. Its sources are located on the Rodopi range, and more specifically on the peaks Korfovouni and Mati located in the regional units of Evros and Rodopi respectively. In antiquity, it was known as Erigonas, while in Bulgarian, it is called Luna Reka, which means 'the crazy river'.

Since 2008, the Municipality of Didymoteicho holds a cultural festival called "Red River Cultural Festival".