Even my youngest boys are outgrowing the sandbox. They used to spend hours creating castles, mountains for their dinosaurs, and race car tracks.
To make the sand box more interesting I used to throw things in it like old kitchen utensils like dented measuring cups, or a colander whose handle was coming off. Even an old cake pan or plastic container can be great for making sand cakes and mud pies. The boys liked to turn the hose on to soak the sand. I thought watering cans were a better idea for moistening the sand since the hose often turned into a flood.
I also used to periodically hide treasures in the sand. The treasures weren’t anything expensive or anything that would be missed if it got lost. I buried things like handfuls of pennies and nickels, some colorful rocks, forgotten shells from a trip to the beach, or a tube of dinosaur toys. Once there were old enough not to swallow them, I also buried beautiful glass marbles and those colorful glass pebbles that people put in vases. Most often I didn’t even tell the kids that I’d hidden something. I just let them play and if they found something they would start digging harder.
If you want to get really fancy you could bury treasures in mint tins. You could even bury clues to a scavenger hunt, coupons for ice cream cones, or pieces to a dinosaur model. Burying things in larger containers makes them easier to find.
Unexpected toys are fun, too. A rubber ducky in a sand box? The kids will build him a pond to swim in. Matchbox cars need a racetrack. And plastic knights need a castle to defend from the dragons.
None of these ideas are hard, or time consuming. But they do add some excitement to that simple sandbox and encourage the very important creative play of childhood.