Ext. Sandman's Castle
Marjolein en het geheim van het Slaapzand - 10 locationsS1a6: Marjolein, Marco & Nicole jumps with Klaas Often on the back of Oehoe Houdoe and flies to Klaas Often's sand castle. Sand castle of Klaas Often in the lake of Efteling Bosrijk.
The interior (the inside) was filmed at an as yet unknown location.