Ocean cold as water at greater depths. Below the thermocline, water is very cold, ranging from −1 °C to 3 °C. Because this deep and cold layer contains the bulk of ocean water, the average temperature of the world ocean is 3.9 °C. If a zone undergoes dramatic changes in salinity with depth, it contains a halocline. If a zone undergoes a strong, vertical chemistry gradient with depth, it contains a chemocline. The halocline often coincides with the thermocline, and the combination produces a pronounced pycnocline. The deepest point in the ocean is the Mariana Trench, located in the Pacific Ocean
World Ocean Database Project Float (PFL), Moored Buoy (MRB), Drifting Buoy (DRB), Gliders (GLD), Autonomous Pinniped Bathythermograph (APB). The data in the World Ocean Database are made available through the online search and retrieval system known as WOD"select". The World Ocean Atlas (WOA"select") series is a set of gridded (1° grid), climatological, objectively analyzed fields of the variables in the World Ocean Database. The WOA"select" is a selection tool by which the user can designate a geographic area, depth, and oceanographic variable to view climatological means or related statistics for a given variable at the requested depth for the requested geographic area. World Ocean