A man is kayaking in rough water.
A man is kayaking on rapids in a river.
Rapids in a river isn't the only place where rough water can be found.
exists e1 s1 x1 x2.(in(e1,x2) & n_water(x2) & a_rough(s1) & Theme(s1,x2) & Actor(e1,x1) & v_kayake(e1) & n_man(x1))
exists e1 x1 x2 x3.(in(e1,x3) & n_river(x3) & on(e1,x2) & n_rapid(x2) & Actor(e1,x1) & v_kayake(e1) & n_man(x1))