The image from our PROBA-V quiz on September 6th, showed the confluence of the Paraná and Paraguay rivers, right on the border between Argentina and Paraguay. The Paraná River, Río Paraná in Spanish, forms the second longest river in South America after the famous Amazon. Its historical name, in local Tupi language, translates to ‘as big as the sea’. In the image, the Paraná flows from the reservoir (east) formed by the Yaciretá dam, a joint development of both countries, towards the west before joining Paraguay river (flowing north-to-south) and heading further south through Argentina. South of the namesake city, it will join the Uruguay River in the Paraná Delta, a large flood plain, and empties in the Atlantic Ocean near Buenos Aires.