Final answer:
The ocean's layered structure consists of the photic zone, aphotic zone, and abyssal zone. In high latitudes, this three-layer structure may not exist.
Step-by-step explanation:
The ocean has a layered structure consisting of different zones based on depth. The top layer is the photic zone, which extends from the surface to 200 m. Below that is the aphotic zone from 200 to 4,000 m, and finally the abyssal zone from 4,000 m to the ocean bottom.
In high latitudes, the three-layer structure may not exist due to factors such as mixing caused by ocean currents and the presence of ice.