Slice into the damp sand with a shovel. Hear music of crystal grains on metal. Smell the salt and damp rot of the sea. Lift the crumbling burden and tip it on the smooth, wave-washed surface. Clumps tumble down the small mound.
Another thrust with the shovel, cleave the sand, make the hole deeper, longer, each shovel-full creates both moat and hill. The rhythm of digging matches the hiss of the waves. Stop to look out over the sea, its deep, mysterious blues that shift with the passing of the day. Drink in the colors that only it can spread in such profusion, cover the earth in indigoes and turquoise.
Finish the moat, a deep rectangle around the lumpy cone at the middle. The boundaries of your imaginary kingdom are set. No stranger will cross them. This is your world now. Toss the shovel aside to lie with the driftwood. Now is the time for hands. Feel the grains on your bare knees, the sun baking the back of your legs and neck. Pound the sand, push it, knead it, shape it. Create plateus and cliffs, spaces for building, places for paths, terraces for gardens.
Now for the water.
Dig again, this time deep enough to find the sea. Down, down into the sand, create a well of saltwater and fine sand. A quarry for the slurry of crumbling, quick-drying cement that will be your building material. Deeper, deeper, and then at the bottom a darkening of the sand, then a gleam of reflected sky. Water.
Reach in and take a handful. Feel it drip down your arm, the flowing grit. Place it on your mound, cup your hands to make it round, wait while the water drains away, leaving the firm base of a tower. Another handful, set it on top, the water liquefies the whole mass into jiggly clay. Shape it, hold it, wait for it to set. Build your towers, layer by layer. Add a building, square, rectangle, or round. Make bridges by supporting the sand slurry from below as it hardens into an arch. Find a stick to carve windows, doors, and stair-steps.
Now for the magic.
Take a handful of watery sand and let it dribble off your fingers. See each drop fall, then freeze, building up a sand stalagmite. Lace your tower tops with sand-drip caps, sharp and pointed. Drizzle railings for the stairs and walls for the gardens.
A wave splashes at your ankles, then sucks the sand from beneath your knees. The next one comes, the water a great paw carving a hollow in the side of your hill. The castle falls into the pit of the moat.
The sea reclaims your kingdom for its own.
Take your shovel and walk a little higher up the beach. Slice into the damp sand.