Oceanography is a means of in-depth study of the ocean in which physics, chemistry, biology and geology help to study each other together. Basically, there are four branches of oceanography which study the ocean in different ways:

Physical oceanography: In this, the nature of seawater (temperature, density etc.), the speed of seawater, the study of waves, currents, tides, and the relationship between the ocean and the atmosphere are studied.

Chemical oceanography: This branch studies and analyses the composition of sea water and the biogeochemical factors affecting it.

Biological Oceanography: Including the study of biological organisms (life cycles and food production, etc.) that inhabit and develop in the ocean, such as bacteria, phytoplankton, zooplankton and fish and marine mammals and other marine organisms and the effects of these and other factors on them.

Geological oceanography:  Studies the structure, characteristics and development of ocean basins. Along with this, it also studies the changes taking place in the composition of the ocean.

Oceanography is more than these specialized branches. Many instruments are used to study the ocean. For this, special knowledge of oceanography is required separately. There is a separate branch of study to collect samples from the sea. Thus, each parent branch has many sub-branches.