Quicksand Fans

I know from experience that quicksand in a tidal marsh can be particularly deadly.

When I was younger, a neighborhood kid went missing. After a few hours search, his parents were ready to call the police. His uncle had gone down to the dock (waterfront house) to sit and think. Apparently he say the top of the kid's head just below the surface. Poor kid was about waist deep in the mud when the tide came in.