The figure took another step, and its foot sunk into the ground.
John jumped away as his feet sank in, and the others did the same.
His feet had sunk perhaps six inches into the earth.
His feet at that time had sunk down six inches with each step.
Our feet sank into the dry red earth as we moved around the rear of the low building.
Your feet sink a little into the soft substance, but you can walk.
Mike's feet sank into the sand as he moved down the beach.
He even saw himself running over the muck, his feet sinking.
The ground does have a sandy color to it, or gray, but your feet won't sink in.
Your feet will sink, but your head should be near the top.