Original: The complex at Den Oever includes the Stevin lock and three series of five sluices for discharging the IJsselmeer into the Wadden Sea ; the other complex at Kornwerderzand is composed of the Lorentz locks and two series of five sluices , making a total of 25 discharge sluices .
Simplified: The sluices let water out of the IJsselmeer . If there were no sluices the lake would fill up and flood the countryside .