of or taking place in the deeper parts of the sea; "deep-sea fishing"; "deep-sea exploration"
of or taking place in the deeper parts of the sea; "deep-sea fishing"; "deep-sea exploration
Deep-sea activities take place in the areas of the sea that are a long way from the coast. deep-sea diving. a deep-sea fisherman. deep-sea fishing or diving is done in the deep part of the sea, far away from land
or oceanic trench Any long, narrow, steep-sided depression in the ocean bottom in which maximum oceanic depths (24,000-36,000 ft, or 7,000-11,000 m) occur. The deepest known depression of this kind is the Mariana Trench. Most trenches occur at subduction zones, where one tectonic plate is thrust under another
Hydrothermal (hot-water) vent formed on the ocean floor when seawater circulates through hot volcanic rocks, often located where new oceanic crust is being formed. Vents also occur on submarine volcanoes. In either case, the hot solution emerging into cold seawater precipitates mineral deposits that are rich in iron, copper, zinc, and other metals. Outflow of these heated waters probably accounts for 20% of the Earth's heat loss. Exotic biological communities are now known to exist around the vents; these ecosystems are totally independent of energy from the Sun, depending not on photosynthesis but rather on chemosynthesis by sulfur-fixing bacteria