Bathypelagic Zone (Midnight Zone)

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Conventionally about 1,000 m to 4,000 m. No measurable sunlight reaches it; NOAA describes the region below 1,000 m as the aphotic zone of eternal darkness, with the bathypelagic running from 1,000 to 4,000 m. Temperature is near-uniformly cold and pressure rises by roughly one atmosphere for every 10 m of depth. Because no light means no photosynthesis, the entire energy budget of this zone is imported from above as sinking particles, or in rare places from chemosynthesis at seeps and vents.