I think your team mates were wrong. Cute pictures of kids did well, but I think this one hits the challenge well, especially the accomplish something worthwhile part and would have been a standout in a sea of cute kids playing.
Yip... This would have doen better on my voting scale. I voted 6 on your entered image. This I would have voted 7 minimum. More purpose. Nice reflection and pleasing angle on the sea with 3 elements holding these three Amigos together nicely - Sky, water and land. What more do you want appart from some rock which would have added to their purpose in diving