There is no motion blur to convey the boys running across... Pic appeals to me but it's more like 'Play at Beach' & Bluestrike is right to get a level shot =)
OR tilt it 5degrees clockwise... diagonal horizons sometimes good =)
the sky and the boys seem to be competing for attention. consider a lengthwise crop? eg:
or even more drastic, remove the sky and just keep the waves + reflections on the sand.
the postures of the three boys on the right convey the impression of movement well; pity about the one on the left as i can't quite figure out what he's doing or which way he's going. the silhouettes and colours work for me.