The Rhine–Meuse–Scheldt delta or Helinium is a river delta in the Netherlands formed by the confluence of the Rhine, the Meuse and the Scheldt rivers. The result is a multitude of islands, branches and branch names that may at first sight look bewildering, especially as a waterway that appears to be one continuous stream may change names as many as seven times, e.g. Rhine → Bijlands Kanaal → Pannerdens Kanaal → Nederrijn → Lek → Nieuwe Maas → Het Scheur → Nieuwe Waterweg (→ North Sea). Since the Rhine contributes most of the water, the shorter term Rhine Delta is commonly used. However, this name is also used for the river delta where the Rhine flows into Lake Constance, so it is clearer to call the larger one Rhine-Meuse delta, or even Rhine-Meuse-Scheldt Delta, as the Scheldt ends in the same delta.
The economic importance of the Rhine–Meuse–Scheldt delta is enormous, since the three rivers are important navigable waterways. The delta is the entrance from the North Sea to the vast German and Central European hinterland (and to a lesser extent France). Major ports in the delta are Rotterdam, Antwerp (Belgium), Vlissingen, Amsterdam (through the Amsterdam–Rhine Canal), and Ghent (through the Ghent–Terneuzen Canal). The land areas in the delta are protected from flooding by the Dutch delta Works.