A couple of times a Summer we take our boat from the CT shore across Long Island Sound to the LI coastline to a gorgeous beach the "regulars" fondly refer to as Magic Beach. It is a beach that is only accessible by boat and not many people know about it. Someone dubbed it Magic beach because it is not covered in sand but in beautiful smooth rocks that when you throw a handful of them they bounce and spark like Magic.
The photo above is the rocks dry, below they are even prettier wet. I used to take handfuls home and put them in jars but now my boys and I make a point of finding one special one in the shape of a heart before we leave (and we always find one!)
The other great thing about this place is that the kids have to be imaginative and find things to do on their own. Last time we went they built this fort from debris and driftwood that has washed up on the shore.