There are four individuals standing together in a line at the waters edge wearing black diving gear with red and black flippers.
People are outside.
People is a shorter term to describe four individuals.  If people are at the water's edge, then they are outside.
exists p1 x1 x5 x6.(n_edge(x5) & of(x5,x6) & n_waters(x6) & exists e1 e2 s1 s2 s3 s4 x2 x3 x4 x7 x8 x9.((x1 = x2) & for(e1,e2) & Theme(e2,x7) & Actor(e2,x3) & v_wear(e2) & with(x7,x9) & n_flipper(x9) & a_black(s4) & Theme(s4,x9) & a_red(s3) & Theme(s3,x9) & n_gear(x7) & of(x7,x8) & n_diving(x8) & a_black(s2) & Theme(s2,x7) & at(e1,x5) & in(e1,x4) & n_line(x4) & a_together(s1) & Manner(e1,s1) & Actor(e1,x3) & v_stand(e1) & (x2 = x3) & n_individual(x2) & card_eq_4(x2)))
exists s1 x1.(Theme(s1,x1) & a_outside(s1) & n_people(x1))