On every beach I can find some creatures, usually small, not so visible at first, but if I sit down on the sand, not too far from the water, I can usually spot some crabs running around and other types of sandy creatures...
Depending on the weather as well, sometimes it is just too hot to move or do anything outside the water. Watching these creatures, chasing and catching them is one of my ways to entertain myself on the beach.
Lying down quietly and listening to the sounds of the waves, the birds catching fish in the water, is one of my favourites... but if the beach is crowded, especially with loud kids and families, then there's probably just one thing left for me to do... go find a quieter beach!