Actually, you are almost required, by the swimming pool code, to have a light in the deepest part of the pool.
I say "almost," because the rule about pool lighting applies only to common pools (say, at apartment complexes) and only if night swimming is allowed.
The reason? The need to be able to see if someone is under water longer than they should be. Overhead lighting is not enough ... the lights need to be IN the pool. and the entire bottom needs to be lit.