Which zone of the ocean is known for the complete absence of sunlight?

The correct answer is the abyssal zone, which is characterized by the complete absence of sunlight. This zone exists at great depths—typically below 2,000 meters (about 6,600 feet)—in the open ocean, where light from the surface cannot penetrate. As a result, the conditions in the abyssal zone are extremely dark, cold, and high in pressure, creating a unique environment that supports specialized life forms.

In contrast, other zones like the neritic zone and intertidal zone are much closer to the surface and experience significant sunlight. The neritic zone is found over the continental shelf, where sunlight can penetrate and foster photosynthesis, and the intertidal zone experiences varying exposure to sunlight due to tidal changes. The epipelagic zone, or sunlight zone, includes the upper layer of the ocean where light is abundant, allowing for a diverse range of marine life to thrive.