Marine Biology requires a lot of  scientific knowledge. If you want to be a marine biologist, its a good idea to take all the courses you can in this area when you are in college.  It will take you at least four years to earn your bachelors degree.  It will take you two to five years to earn your masters degree.  Its a good idea to get experience in the lab and in the real marine habitat.  You could also get a job during the summer on the weeekends( that helps a lot!).  Also, before graduation you should consider getting a job as a vet's assistant, or a zoo and wildlife worker.