A person on a surfboard in the ocean.
Someone is on the water.
The ocean is water.
exists x1 x2 x3.(n_ocean(x3) & a_topic(x1) & on(x1,x2) & in(x2,x3) & n_surfboard(x2) & n_person(x1))
exists p1 x1 x2.(n_water(x2) & on(x1,x2) & n_person(x1))