A person swimming underwater poses for a picture with some underwater vegetation.
A swimmer poses with sea weed.
Just because the person poses with underwater vegetation doesn't necessarily mean that it is sea weed instead of some other type of vegetation.
exists e1 x1 x2 x3 x4 x5.(for(e1,x3) & with(x3,x4) & n_vegetation(x4) & of(x4,x5) & n_underwater(x5) & n_picture(x3) & Actor(e1,x1) & v_pose(e1) & n_swimming(x1) & Time(x1,x2) & n_underwater(x2) & n_person(x1))
exists e2 e1 x1 x2 x3.(with(e1,x2) & Theme(e2,x3) & v_weed(e2) & (x2 = x3) & n_sea(x2) & Actor(e1,x1) & v_pose(e1) & n_swimmer(x1))