Summer’s blue skies and warm temperatures beckon us to the beach. After all, summer is synonymous with fun in the sun, surf, and sand. And what is a day in the sand without building a sandcastle? While rising tides can be every sandcastle builder’s enemy, the ocean is also their greatest ally. That’s because damp sand sticks together, allowing sandcastle magic. Dry, powdery sand may feel nice but it’s no friend of castle building and a large part of that is down to cohesion. Quick tests of moist and dry sand showed a 10x difference in cohesion!