Sir Cornelius Vermuyden (Sint-Maartensdijk, 1595 – London, 11 October 1677) was a Dutch engineer who introduced Dutch land reclamation methods to England. Commissioned by the Crown to drain Hatfield Chase in the Isle of Axholme, Lincolnshire, Vermuyden was knighted in 1629 for his work and became an English citizen in 1633. In the 1650s, he directed major projects to drain The Fens of East Anglia, introducing the innovation of constructing washes, to allow periodic flooding of the area by excess waters.