What is the abyssal zone?

The abyssal zone is a deep layer of the ocean's pelagic zone characterized by perpetual darkness, freezing temperatures, and extreme pressure. Spanning thousands of meters below the surface, it lacks sunlight and photosynthetic plants, relying instead on dissolved oxygen from ancient melted polar ice and nutrients from decaying organic matter drifting down from above. Below it lies the hadal zone, while the bathyal zone sits above.

What we know

• The abyssal zone, also known as the abyssopelagic zone, is located at depths between 4,000 and 6,000 meters. [1, 2]
• The zone remains in perpetual darkness, preventing photosynthesis and the local production of molecular oxygen by plants. [2]
• Water temperatures in the abyssal zone remain around 2 to 3 degrees Celsius across the vast majority of its mass. [2]
• Water pressure in the region can reach up to 76 megapascals, equivalent to 750 atmospheres. [2, 3]
• Molecular oxygen in the abyssal waters primarily originates from ice that melted long ago in the polar regions. [2, 3]

Where to go next

• a case in pointWhat lies beneath the abyssal zone in ocean trenches?
• how it workedHow do flat underwater plains form at these extreme depths?
• what caused itWhat environmental management issues affect deep-sea regions like the Clarion-Clipperton zone?
• the bigger pictureHow does the pelagic zone categorize different vertical layers of the ocean?
• compared withWhat are the differences between the bathyal zone and the abyssal zone?
• an unexpected connectionHow is deep ocean oxygen connected to ancient melted ice?Because the abyssal zone lacks sunlight and plant life, the dissolved oxygen sustaining its sparse life primarily originates from ancient melted ice in the polar regions.

Sources

• [1]abyssal zone (Wikidata Q242857) · CC0 1.0
• [2]Abyssal zone · CC BY-SA 4.0
• [3]Abyssal plain · CC BY-SA 4.0
• [4]Hadal zone · CC BY-SA 4.0
• [5]Clarion–Clipperton zone · CC BY-SA 4.0