well, there are three different zones:
sunlight zone: the brightest; plants and algae can grow there, home to many ocean animals, and shallowest of zones
twilight zones: dimmer and colder water; plants an algae can not liver there; ocean animals that liver here live in darkness and many have big eyes
then there is the midnight zone: super cold and pitch black, food is scarce and few ocean animals liver there.
my best answer would be the sunlight zone...