noun
bathyal zone; midnight zone; bathypelagic zone
Oceanographic term for the depth zone roughly 200–4,000 meters, where sunlight does not penetrate. Used in scientific and educational contexts.
漸深海帯には、発光する生物が多く生息している。
Many bioluminescent organisms live in the bathyal zone.
この深海魚は漸深海帯でよく見られる。
This deep-sea fish is commonly found in the midnight zone.
Compound of 漸 (gradual, approaching) + 深海 (deep sea) + 帯 (zone), literally 'zone approaching the deep sea'. The term is a calque from Western oceanographic classification.