<p>
For marine biology, a biology major is usually the best stepping stone. Oceanography, the broader field, is a bit different – depending one one’s concentration, it’s feasible to major in biology, chemistry, geology, physics, or even engineering.</p>
<p>As for specific requirements, UCSD and MIT are reasonably specific about the minimums:
Keep in mind that these are minimums…marine biology programs are quite competitive, and a strong applicant would go well above that. Additionally, decent undergraduate research is going to need more than the standard biology sequence for pre-med.</p>
<p>If you are interested in other areas of oceanography, the background necessary would change. Physical oceanography requires a fair amount of upper-level math and physics (e.g. fluid dynamics, thermodynamics, partial diff eqs, etc.), whereas for geological oceanography, a background in sedimentology, geomorphology, (micro)paleontology, etc. would be more helpful. Chemical oceanography requires a background in inorganic and organic chemistry, analytical chemistry, physical chemistry, and some math. Archaeological oceanography requires a background in any of these fields plus a basic knowledge of anthropology. Basic computing skills are, of course, presupposed for all of these fields.</p>
<p>For marine policy or fisheries science, a background in public policy and econ would be quite helpful in addition to a science background.</p>