Four people are in a boat moving across a lake that's surrounded by trees.
Four people are outdoors.
A lake is outdoors, so people moving across a lake are outdoors.
exists p1 x1.(exists e1 e2 x2 x3 x4 x5 x6.(in(x1,x2) & across(e1,x4) & Actor(e2,x6) & n_tree(x6) & Theme(e2,x5) & v_surround(e2) & (x4 = x5) & n_lake(x4) & Actor(e1,x3) & v_move(e1) & (x2 = x3) & n_boat(x2)) & n_people(x1) & card_eq_4(x1))
exists p1 x1.(exists x2.((x1 = x2) & n_outdoors(x2)) & n_people(x1) & card_eq_4(x1))