What is Sinking Sand?

Context: Quicksand, also known as sinking sand, is a colloid consisting of fine granular material and water. It forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it creates a liquefied soil that loses strength and cannot support weight. Quicksand can form in standing water or in upward flowing water. In the case of upward flowing water, forces oppose the force of gravity and suspend the soil particles.

Answer: Sinking Sand is most commonly known as Quicksand.