The Pelagic Zone Contains the Largest Volume of Ocean Water

The ocean's three major life zones are intertidal, neritic (continental shelf), and pelagic (open water). The pelagic zone is by far the largest by volume, subdivided vertically:

• Epipelagic (0–200 m): Sunlit, photosynthetic.
• Mesopelagic (200–1,000 m): Twilight zone.
• Bathypelagic (1,000–4,000 m): Midnight zone.
• Abyssopelagic (4,000 m–floor): Abyssal zone.
• Hadopelagic (trenches >6,000 m): Hadal zone.

Together, pelagic waters comprise >90% of ocean volume—Earth's largest habitat.