This stuff looks like chocolate, but you shouldn't eat it. There's probably a chocolate factory nearby, and this is their waste pond. But Lucy has a known sweet tooth, and the smell of chocolate seems to attract her to this place. Getting too close to the edge of the pond, she falls right into the brown quicksand. This is where her journey to the bottom begins.
Lucy struggled and resisted sinking into the brown mud. She tried to reach the shore, grab onto the grass, but in vain. Lucy moved so vigorously that her boobs were exposed. Despite her efforts, she sank lower with each movement. Eventually, Lucy disappeared under the surface.
In the bonus video, Lucy dives into the mud several times, then emerges and escapes from the quicksand trap.
Note: This is a fantasy scene intended to entertain fans of women in peril. Nobody was harmed during the filming of this scene.