Four swimmers in the crystal blue ocean with yellow surfboards.
The swimmers ride on their surfboards in the ocean.
Swimmers with surfboards does not mean they  ride on it, they may just be carrying it.
exists s1 s2 s3 x1 x2 x3.(n_ocean(x2) & a_blue(s2) & Theme(s2,x2) & a_crystal(s1) & Theme(s1,x2) & a_topic(x1) & in(x1,x2) & with(x2,x3) & n_surfboard(x3) & a_yellow(s3) & Theme(s3,x3) & n_swimmer(x1) & card_eq_4(x1))
exists e1 x1 x2 x3.(n_ocean(x3) & n_surfboard(x2) & of(x2,x1) & n_thing(x1) & n_swimmer(x1) & in(e1,x3) & on(e1,x2) & Actor(e1,x1) & v_ride(e1))