Must have been impressive indeed if that was the first time. I don't remember anything that spectacular in Holland but we did have an area in the south near us where it was all dunes, like in the middle of nothing haha.. When I had dogs I often went there to let the dogs play.. but the sand was not as cool looking as it is in your pics. I never really understood why these dunes were there in Holland as there was no see near.. Gosh need to google it now :)
Have a great day!