This lock consists of two gates equipped with large counterweights. Together with the identical Low Knarsluis in the Lage Vaart, the High Knarsluis, in combination with the Knardijk, prevents the entire Flevopolder from flooding in the event of a dike breach. By closing both locks, the inundation (flooding) is limited to half of the Flevopolder.

Next to the High Knarsluis, there is a small sheltered harbor with a moderately maintained visitor's jetty. It is named after the former channel or sandbank De Peppelt, which was located nearby. During the former Zuiderzee era, ships used this as a point of reference.