Oceanographers study all aspects of oceans: plants and animals, rocks and reefs, currents, tides and water circulation, seashores and the world's atmosphere.
Oceanographers usually focus on one of four main disciplines:
Marine biologists study plants and animals in the seas and oceans investigating their environment and any adaptations due to temperature or pollution
Marine chemists deal with the chemical composition of seawater and may also involve the effect of pollution
Marine geologists investigate the seabed's structures, composition and history; they may work in industry discovering and extracting minerals, oil and gas; or advise on pipeline location, cables and the safe disposal of toxic material
Marine physicists deal with tides, currents, temperature and barometric pressure and may analyse the influence of moon cycles or solar flares; recent developments include the harnessing of wave energy
While it is possible to gain a technician level job with two science based A-levels (preferably physics, chemistry or biology), most new entrants have degrees.
Relevant degrees include oceanography, marine science, marine biology, chemistry, and biochemistry. In fact, almost any natural science degree is useful. Degrees usually require a minimum of two science based A-levels, often three.