Answer:
The Bathyal zone is the hardest to survive in.
Explanation:
Technically, the entire ocean is difficult to survive in. There's no oxygen and lots of scary ocean predators.
But the Bathyal zone, which is 1000 - 4000 meters below the surface of the ocean has no sunlight, making most of the sea creatures there have no eyes. Because this zone is so dark, with little food to survive in, fish don't hang out here.
(I suggest just staying home)
