Delta Works was completed by the Europoortkering which required the construction of the Maeslantkering in the Nieuwe Waterweg between Maassluis and Hoek van Holland and the Hartelkering in the Hartel Canal near Spijkenisse. The works were declared finished after almost forty years in 1997. In reality the works were finished on 24 August 2010 with the official opening of the last strengthened and raised retaining wall near the city of Harlingen, Netherlands. Due to climate change and relative sea-level rise, the dikes will eventually have to be made higher and wider. This is a long term uphill battle against the sea. The
European land exploration of Australia discovered—the Darling, Macquarie, Murray and Murrumbidgee rivers—all of which flowed west, a theory was developed of a vast inland sea into which these rivers flowed. Another reason behind the idea of an inland sea was that Matthew Flinders, who had very carefully mapped much of Australia's coast had discovered no great river delta where these rivers should have emerged by had they reached the coast. The Murray-Darling basin actually drains into Lake Alexandrina. Matthew Flinders had noted this on his maps but viewed from the sea does not look like the outfall of a large watershed, but instead as a