Mud and sludge, which many simply call mud, are fine-grained material or clay. It is a natural part of the Wadden Sea, deposited in connection with the movements of the tides. In Sønderho Harbor, where the water almost stands still twice a day, the fine material is deposited, which, unlike sand, has poor load-bearing capacity. Therefore, if you venture beyond the water's edge, you will experience that your shoes and boots sink into the mud. It is certainly not pleasant, and it can be difficult to get the rubber boots back up.
So do not let your children venture into the water, even though it may be tempting!