Quicksand is a colloid hydrogel consisting of fine granular material (such as sand, silt or clay), and water. In the dimension of Jumanji, Quicksand serves as a natural trap for herbivores or predators, leading to either drowning from total submerging or dying from exhaustion trying to drag themselves free.
Quicksand may be found on riverbanks, near lakes, in marshes, or near coastal areas. Quicksand 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 upwards flowing water (as from an artesian spring). In the case of upwards flowing water, seepage forces oppose the force of gravity and suspend the soil particles.
The saturated sediment may appear quite solid until a sudden change in pressure or shock initiates liquefaction. This causes the sand to form a suspension and lose strength. The cushioning of water gives quicksand, and other liquefied sediments, a spongy, fluid-like texture. Objects in liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced soil/water mix and the submerged object floats due to its buoyancy.
After the Monsoon, the players set Jumanji up in the attic and carried on playing with Alan's turn. His dice roll triggered the appearance of Quicksand (which is actually created from the attic floor). Alan was instantly within the field and began to sink, his friends trying to pull him out to no effect because of the leverage breakages. Sarah finally laid on an old door and grabbed Alan to stop him from being total submerged, while Judy rolled her turn to try and resolve the situation, apparently ending the Quicksand effects entirely; but left Alan and Sarah stuck in the floor and unable to move. They were both rendered unmovable which left them vulnerable to persistent giant Spiders, only backing off when Sarah's last turn unleashed an Earthquake, which tore the Parrish Mansion up and set them free from the floor.
- Secret symbol: Axe
- Number: 3
In the Milton Bradley board game, Quicksand has its own danger card. Rolling an Axe on the rescue die within 3 seconds will defeat the Quicksand threat.
Quicksand appears in the animated series as dangerous environmental hazards, but it can also be a good method of chase evasion if carefully avoided. One such instance being in Master Builder; when Alan, Judy and Peter were chased by on of Professor J.S. Heinrich Ibsen's steampunk Hippopotamus, which sank in quicksand beach of it's weight and inability to drag itself free. In Night of the Hunters; Alan is nearly caught by the two hunters, but escapes while they're arguing and Van Pelt starts to sink in quicksand. Alan saves him after he tosses away the rifle, but regrets saving his archenemy when Van Pelt tries to kill him with a pistol and fails.