A marine scientist uses their knowledge of natural science to study and explore the various phenomena that occur in the ocean. In many cases, those who wish to start their career as marine scientist major in the natural sciences such as physics, chemistry, biology, geology, and oceanography in university, and further study more specialized area of oceanography in graduate school. Related disciplines include physical oceanography, chemical oceanography, biological oceanography, and geological oceanography. To work as a researcher, it is common to earn a Ph.D. degree.

A marine engineering researcher designs vessels and underwater structures, as well as ports that are efficient. He/she also designs electric power stations that can generate electricity using tidal range, waves, or temperature differences in the sea. Marine engineering researchers are also involved in designing technology to prevent accidents that may occur in the sea. Related businesses include ocean and resources development, seabed petroleum development, marine structure design and manufacturing, port equipment development, and ocean environment related companies.

A marine geologist explores the origin of the earth by investigating the continental shelf, continental slope, seabed, and then drawing up detailed underwater topographic maps. He/she also examines sediments, seabed rocks and other materials accumulated at the bottom of the ocean from the coastal areas to the deep sea. Marine Geologists also study the history of marine geological changes as well as climate change.

A marine physicist mainly studies the temperature and density of the sea, the movement of waves, and physical traits of tidal and ocean currents. As the physical traits of seawater such as water temperature and salinity are closely related to the movement of seawater, he/she primarily measures the temperature and salinity of seawater. Within the field of physical oceanography, marine physicists also study the interaction between the atmosphere and the ocean and use numerical models to predict changes in the physical environment of the ocean. Marine physicists may also use data collected from satellites to examine the physical environment of the ocean on a global scale (e.g. circulation of sea water and heat balance) and use radar to investigate surface layer currents and waves by observing the tiny wrinkles on the water surface.

A marine biologist refers to a scientist who studies marine life to identify phenomena and processes in the ocean. He/she explores how marine life lives in the sea by observing the relationships between microorganisms, plants and animals or their relations with the surrounding environment. For this purpose, the marine biologist examines the distribution, life cycle, and physiology of marine living things and investigates the nutrition dynamics between them within the food web.

A marine chemist analyzes chemical components that make up seawater and studies the interactions between the sea, atmosphere and seabed. Ocean pollution caused by human activities is also within his/her field of study. Using a variety of precision analysis equipment, the marine chemist studies micro-chemical substances in the sea water such as radioisotopes, heavy metals, and sea salt. Acidification of the sea water by global warming and the flow of carbon dioxide through ocean surface are other areas of research that involve marine chemists.

A geophysicist studies the structure and dynamic movement of the interior of the earth beneath the seabed crust using elastic wave sounding equipment. Using Geophysicists are also involved in the search for oil fields in the deep sea.

A marine engineering technician investigates and analyzes the baseline data for port development, and construction of coastal industrial complexes. They may also use their expertise to supervise the construction projects themselves. In addition, the technician investigates, measures, and evaluates the current state of the marine environment and designs plans related to it. He/she develops pollution prevention and early detection technology by analyzing the cause of red tide and the spread route and the movement of coastal currents; provides basic data of the marine environment; develops oceanographic observation systems; and explores deep sea mineral resources. The technician needs deep knowledge in marine environment and resource development, as well as an analytical mind for collection and exploration of deep-sea resources. Since the field requires a constant academic approach, the ideal candidate must have professionalism and a sense of duty, academic adaptability and an open mind. Candidates normally major in marine engineering, shipbuilding engineering, naval architecture, environmental engineering, industrial engineering, industrial systems, or engineering at a vocational college or university.