They look like they are really enjoying themselves! Sandboxes are the best. My mom has a picture of all five of us kids (youngest at the time was maybe...four or so, so the oldest would have been 16) playing in our sandbox together. ^^ I remember as a child being really mad because Blackie, our Lab, would come and lay down in the box to help cool off in the summer - even if we happened to be building things in it at the time. Lol