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
Litke Deep Litke Deep Litke Deep () is an oceanic trench in the Arctic Ocean. It is the deepest known point in the Arctic Ocean. It is the 20th deepest oceanic trench in the world. The Litke Deep is located in the southwestern part of the Eurasian Basin south of the underwater ridge Gakkel Ridge roughly 350 kilometers northeast of Svalbard and roughly 220 km north of the island of Nordaustlandet. The deepest part is at 5,449 metres (17,881 feet) under sea level. The average depth in the Arctic Ocean is about 1,000 metres and more than 60 % is less than