Which marine zone lies below the intertidal zone and remains underwater at all times, often extending to the continental shelf?

• A. Supralittoral Zone
• B. Pelagic Zone
• C. Sublittoral Zone
• D. Intertidal Zone

Answer: (C)

Coastlines are divided into zones by tides, and the key idea is which part stays submerged regardless of the tide. The area below the intertidal zone stays underwater at all times and typically extends to the edge of the continental shelf. This is the sublittoral (subtidal) zone, a nearshore belt that remains continuously submerged and hosts habitats like kelp forests and other subtidal communities. The supralittoral is above the high-tide line and exposed to air, while the pelagic zone refers to the open water column rather than the seabed near shore. Therefore, the described zone is the sublittoral zone.