sand castle - A sandcastle is a type of sand sculpture resembling a miniature building, often a castle. The two basic building ingredients, sand and water, are available in abundance on a sandy beach, so most sand play takes place there, or in a sandpit. A variant on the sandcastle is the drip castle, made by mixing the sand with water and dripping it from a fist held above. Some refer to the technique as 'dribbling.' When the slurry of sand and water lands on existing sand structures, the effect is Gaudi-esque. Sand castles are typically made by children, simply for the fun of it, but there are also sand sculpture contests for adults that involve large, complex constructions.