Here's a simple answer: State in which water-saturated sand loses its supporting capacity and acquires the characteristics of a liquid. Quicksand is usually found in a hollow at the mouth of a large river or along a flat stretch of stream or beach where pools of water become partly filled with sand and an underlying layer of stiff clay or other dense material prevents drainage. Mixtures of sand, mud, and vegetation in bogs often act like true quicksands. Any sand may become "quick" if its effective weight is being carried by water between the grains. In that case, even a footstep may collapse the loose structure. The sand-water suspension is denser than an animal or human body, so the body cannot sink below the surface, but struggling may lead to loss of balance and drowning. To escape from quicksand, all you have to do is not to panic, but to raise your hands and lift your head up, do not move and just calm down. --The trick for escaping is to slowly wiggle the feet and legs, allowing water to flow in. People float in quicksand so it is also impossible to sink all the way in, but quicksand usually forms at river estuaries, so a captive could drown at high tide.