Five depth zones have been identified in the ocean. Life is most abundant in the uppermost ‘euphotic’ layer, where photosynthesis occurs. The mesopelagic is practically dark, and many creatures hide here during the day. The bathypelagic zone begins at 1,000 metres, where the pressure is nearly 100 times greater than at the surface. Below that lies the abyssopelagic zone, down to the sea floor – except where ocean trenches cut through the sea bed, creating what is called a hadopelagic zone.
