Everyone wants to be a marine biologist until they realize that it involves a little more than swimming with the dolphins and going SCUBA diving.
U Miami had a 95% dropout rate of marine biology majors by their sophomore year!
Japanese studies have 50-60% dropout in the first year, and the people that finish it are limited as well. Out of the 70sth people that started in my class, only three got the MA.

Marine science is wonderful though, the world needs way more of these people than we have.