A rapid change in temperature with depth in the ocean is called thermocline. A rapid change in density with depth in the ocean is called the pynocline.Thermocline
pycnocline
Thermocline
the pelagic zone
The open ocean of any depth, where animals swim or float freely is called a pelagic zone. Salinity variations in the open ocean normally ranges from 33 to 38 percent.
Pycnocline
halocline
That technique is called sonar.
The average depth of the Indian ocean is I dont know honestly
Depth is a measure of distance between the surface and the ocean floor.
the darkest part of the ocean is the bottom of the ocean
The average depth of the Atlantic ocean is 10,955 feet. The deepest part of the ocean is about 28,232 feet deep in an area called the Milwaukee Deep.