The ocean contains approximately 97% of Earth's water within a system of interconnected basins that cover 71% of its surface. Coastal systems mostly extend seaward from the high-water mark, or just beyond, to the edge of the continental shelf and include shores of soft sediments, rocky shores and reefs, embayments, estuaries, deltas and shelf systems. Oceanic systems comprise waters beyond the shelf edge, from ~200 m to nearly 11,000 m deep , with an average depth of approximately 3700 m. The epipelagic zone, or upper 200 m of the ocean, is illuminated by sufficient sunlight to sustain photosynthesis that supports the rich marine food web. Below the epipelagic zone lies the barely lit mesopelagic zone , the perpetually dark bathypelagic zone  and the deep seafloor , which spans rocky and sedimentary habitats on seamounts, mid-ocean ridges and canyons, abyssal plains and sedimented margins. Semi-enclosed seas  include both coastal and oceanic systems.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report