I'm going for marine biology starting in august of this year! I know the job market is not that big, but I think if I can't find something in marine biology I will try to do something in environmental/conservation biology. With all the focus on saving the planet now, I think there will be more jobs in that area in the coming years.
I'm actually going into Marine Biology and I'm not too sure what I wanna do in the field either. I'm sure finding a job in this field, you have to be really good and top of the class. But either way I think the job market for Marine Biologist will expand due to the overwhelming problems effecting us globally, like coral bleaching, island erosion, water pollution, global warming, the list goes on.
Hopefully by the time I graduate many years down the road, the economic crisis will be resolved too. Or I can just stay in school forever until it's over haha.
Also for those who keep mentioning going into biology as an undergraduate, some schools actually offer undergraduate Marine Biology/Oceanography programs.
As for classes, I think it's different for different schools but as most people have said, science is most likely the bulk of the classes you will be taking. Here is a layout of the courses that are required for my school.
Core Requirements:
http://catalogs.rutgers.edu/generated/nb-ug_current/pg23718.html
Marine Biology Courses for Undergraduate and Graduate:
http://marine.rutgers.edu/courses/index.html
Here is a link to the School of Arts and Science (SAS) and School of Environmental and Biological Science (SEBS) Marine Biology Major listing with other links with more information.
The Rutgers University website is bit much and hard to navigate at times. There is so many students/programs/information all over the place and there is a different website for everything at Rutgers. It's a bit annoying. But I would suggest looking up which Universities/Colleges you are interested in and most colleges have a course layout like my University.
GOOD LUCK!