at this time were the two main branches of the Rhine. The Waal flowed into the Meuse in the Roman period. Pliny the Elder's Natural History gives a list of tribes living in the "Gaulish islands", within the delta region between different mouths of the Rhine. First, he mentions the large island of the Batavians and the Cananefates. Then he gives the list of other peoples who he says are stretched out along 100 Roman miles, between the mouth of the Helinius (understood to be the main mouth of the Meuse, where the Waal () also discharged) and the Roman fortification at Flevum (a port north of the Old Rhine). The Roman castrum at Flevum was mentioned by Tacitus, and is equated today with Velsen. Although the details are no longer clear, there was apparently sometimes an extension of the Old IJ that came close to the north sea here. But the term Flevo was also have used by Pomponius Mela to refer to the fresh water lakes which were in the area of the modern Zuiderzee, which Mela specifically says that the Rhine fed into. So the Rhine mouth mentioned by Pliny might have been a discharge into a lake, or perhaps water running to Flevum on the coast may have run via the lakes to the coast, perhaps first through an ancient version of the Vecht, or the IJssel. The IJssel however was joined to the Rhine artificially, by Drusus, and is quite far from any of the places known to be called Flevus. Suetonius says that this channel was still referred to as Drusus' fossa in his time. Some authors have argued that the mouth Pliny mentions is the Vlie, much further to the north than Velsen where the main waters of the lake entered the North Sea. Emissaries There are actually five emissaries, namely; Haringvlietdam (dam blocking the Haringvliet) Nieuwe Waterweg (canal connecting Rotterdam to the North Sea) North Sea Canal, connecting Amsterdam to IJmuiden Afsluitdijk, damming off the Zuiderzee, with discharging sluices at two places (Stevinsluizen at Den Oever and Lorentzsluizen at Kornwerderzand). References External links State of the art on academic research in the Rhine-Meuse-Scheldt delta River deltas of Europe Landforms of the Netherlands