I agree that your focal point would be diluted if you have two strong lighting sources. If you choose to do that, I would suggest making sure one of them if a lot stronger than the other. I would also move your character a bit more to the right. He is not RIGHT in the middle, but almost. I think if he was a little lower as well it would increase the tension (now, he is so close to reaching the surface that it's almost certain he will make it.)
Hope it helps!
Love it! :)