De Volharding (English: The Perseverance) is a smock mill in Jislum, Friesland, Netherlands which was built in 1872.

The mill has been restored to working order and designated as being held in reserve in times of emergency.

[2] It drained the Ald Piip Polder,[3] which has an area of 50 hectares (120 acres).

In 2006, the mill was officially designated by Wetterskap Fryslân as being held in reserve for use in times of emergency.

Each revolution of the screw lifts 900 litres (200 imp gal) of water.