In some places in the world that is a real version of Quick Sand, it's not like in the Movies where you sink till it's over your head. In big tidal flows, people get stuck on the mud flats, it doesn't take much. Just up to your knees and when the tide comes in you drown. Local rescue teams have a strategy where they pump water into the mud you are stuck in making it more sloppy so you can break the suction, which is really time-critical with a fast-approaching tide. I once got my dirtbike stuck in wet sand on a creek bed, the more I dug the deeper it got. Bloody hard work breaking that suction. The wildest ground I ever rode over was a valley that had a Piet Bog in it, it was okay if you didn't break the surface. The odd thing was you could cause it to bounce and ripple with your foot like a trampoline. Brake the crusty surface and it was wet sloppy mulch and stunk really badly.