Openocean

Open ocean refers to the portion of the marine environment beyond the edge of the continental shelf. It covers the pelagic zone, from the surface down to the deepest trenches, and is distinct from nearshore coastal waters and benthic seabed habitats. The open ocean is commonly divided into vertical zones by depth and light: epipelagic (0–200 meters), where photosynthesis occurs; mesopelagic (200–1000 meters); bathypelagic (1000–4000 meters); abyssopelagic (4000–6000 meters); and hadopelagic (below 6000 meters) in deep trenches.

Organisms range from microscopic phytoplankton and zooplankton to nekton such as fish, squid, marine mammals, and large jellyfish. Primary production is concentrated in sunlit layers and upwelling regions; much of the open ocean has relatively low nutrient levels, resulting in lower productivity per area but occupying most of the ocean’s surface.

Open-ocean oceanography is shaped by currents, temperature, salinity, and oxygen distribution. Thermoclines and oxygen minimum zones influence habitat suitability, migration patterns, and food webs. Human impacts include climate change, overfishing, plastic pollution, and shipping, which can disrupt ecosystems and biogeochemical cycles. Research methods such as satellite observations, autonomous vehicles, buoys, and ship-based sampling are used to monitor physical conditions, circulation, and biodiversity. Conservation efforts encompass international agreements and protected areas aimed at sustaining open-ocean ecosystems and the services they provide.