Quicksand can look dry, like sand on a beach. But it is a mixture of clay, either sand or silt, and water—mostly water. Together, the ingredients form a jellylike mass with sand mixed throughout. When someone steps onto the quicksand, the mixture is jiggled. Then it flows like a liquid, and the sand starts sinking to the bottom. The more the person struggles, the more watery the quicksand becomes. A person won’t sink under, at most about halfway. Still, quicksand is dangerous because the thick sand below may trap a person far away from help.