The kids will sleep soundly after frolicking by the seaside at Playa de Miramar. Look for crabs and other little critters, stick a toe in the water or throw a ball around!
You'll find this stretch of coastline in Ceuta. Once you've done all you can at Playa de Miramar, head to nearby Fnideq Beach, Fnideq Mosque, and Gran Casino de Ceuta.