connecting with the Haarlemmermeer (Lake Haarlem) and seriously threatening the cities of Haarlem and Amsterdam. Plans were put forth to reclaim both the Haarlemmermeer and the IJ and turn them into polders. The Haarlemmermeer was first, falling dry in 1852, and the largest part of the IJ followed suit between 1865 and 1876, with only a small lake remaining at Amsterdam that was closed off from the Zuiderzee by the Oranje locks. At the same time, the North Sea Canal was constructed in the former IJ basin to provide Amsterdam with access to the sea again and revive its ailing port. It cut through the isthmus to connect to the North Sea near the town of Velsen; a new port, IJmuiden ("IJ's mouth") was built at its west end. The east end of the IJ polders near Amsterdam was given over to industry, and a large new seaport area was constructed. The Buiten-IJ hosted the mixed dinghy sailing events for the 1928 Summer Olympics in neighboring Amsterdam. It also hosted two events for the 1920 Summer Olympics in Antwerp. The nautical event SAIL Amsterdam takes place on and around the IJ. References External links Former bays Geography of Amsterdam Lakes of the Netherlands Landforms of North Holland Olympic sailing venues Venues of the 1920 Summer Olympics Venues of the 1928 Summer Olympics