A blond child is wearing blue goggles and a green Speedo tank top while swimming underwater.
Some other children are also swimming.
One child swimming does not mean there are some other children swimming.  The child could be swimming alone or with adults.
exists e1 e2 s1 s2 s3 x1 x2 x3 x4 x5 x6 x7.(while(e1,e2) & Theme(e2,x7) & Actor(e2,x1) & v_swim(e2) & n_underwater(x7) & Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & subset_of(x4,x2) & n_top(x4) & of(x4,x6) & n_tank(x6) & of(x4,x5) & n_speedo(x5) & a_green(s3) & Theme(s3,x4) & subset_of(x3,x2) & n_goggles(x3) & a_blue(s2) & Theme(s2,x3) & n_child(x1) & a_blond(s1) & Theme(s1,x1))
exists e1 s1 x1 x2.(n_child(x2) & a_also(s1) & Manner(e1,s1) & Actor(e1,x1) & v_swim(e1) & -(x1 = x2) & n_child(x1))