The children are near a large pile of sand that is next to the water.
The children are outside.
Near a large pile of sand that is next to the water, implies that the children are outside.
exists p1 x1 x5.(n_water(x5) & n_child(x1) & exists s1 s2 x2 x3 x4.(near(x1,x2) & of(x2,x3) & to(s2,x5) & Theme(s2,x4) & a_next(s2) & (x3 = x4) & n_sand(x3) & n_pile(x2) & a_large(s1) & Theme(s1,x2)))
exists s1 x1.(n_child(x1) & Theme(s1,x1) & a_outside(s1))