Quicksand is an area of earth, usually muddy or sandy, that tends to swallow anything stepping on it. The topic began when users on Neoseeker started reporting incidents around the city involving quicksand. The very first report regarding quicksand states that if a bike bangs into a wall, Tommy can get trapped in the floor, upon falling off the bike. However, this report wasn't about an actual quicksand, but about a concrete floor being non-solid.
Years later, videos were uploaded on YouTube that featured actual quicksand in the North Beach with pedestrians being trapped in the sand at times. The area when the quicksand is located is near the Eddie's sign.
However, it is unknown if this glitch is intentional to make it seem like quicksand.