Well I ended up not using my Marine Bio background after leaving school as I am currently attending culinary school, but I have some advice if you really want to work with the fishes outside of a lab some day.
To start get dive certified. A cert program and a fairly sturdy gear package will run you 600 to 700 dollars, and you can spend thousands if you have it at your disposal. Ok now on to the fishes.
I attended UC Santa Barbara, which has a fairly extensive and well funded marine science lab. Most of the other coastal UC schools (University of California for you non Cali types) have these facilities as well. Those that come to mind that have a lot of opportunities are UC Berkeley, UC Santa Cruz, UC San Diego, and if you are not interested in going to a UC type school Calif. State Univ. Monterey.
Ok now that we got the list of schools (there are others on the east coast and in the south, Woods Hole and Texas A&M, even MIT for example, but who doesn't want to live here?) you need to find a school that has a research diver program that will take undergrads. UCSB and UCSC (UCSC has lots of seal and great white research if you like adrenaline) both do, been to both schools and dove for both. You can write or call the others. To become a reasearch diver for the UC system you will go through a 100 hour program that will teach you everything from mixed gas diving, to underwater cartography, to search and rescue. At SB through their program I received both my advanced cert, as well as my rescue cert while in the program. My school also sponsored my dive master certification, but I have to pay the annual insurance myself now as it has been about 5 years.
Ok so now you are a diver with a certificate to work for the school... what next? Well if you are already a bio or marine science person you go directly to your professors and ask them to get a list of graduate students working in their lab, or maybe even the instructor him/herself. If you are a communications major or something you will probably need to take some bio classes to get a basic background in what you will be studying. If you can find a good project or lab to work in in your freshman year, it will guarantee you work for your full tenure at school. Most of the dives I did were voluntary, so do not plan on paying your way through school, but by the time I got out I had over 500 logged research dives under my belt, had worked for Woods Hole, Scripps, and the Moneterey Bay Aquarium, as well as some diving work for PG&E, ARCO, MMS, USGS, and the Navy.
Take aforementioned experience, the contacts you have made, add the references from the dozens of instructors and grad students you have likely worked for and you have a resume that will get you into those 10 good jobs per year. Also if you want to persue a Masters or PhD you will already have an Instructor to support you, as well as a project most likely.
Cooincidentally I have 9 months studying wrasses in moorea, 5 months at Vandenburgh AFB studying withering food disease in Black Abalone, and 4 months at the channel islands NMS looking at eel grass and pipefish under my belt because I was outgoing and willing to try anything. Most people would spend a lifetime saving to afford those kinds of interractions with fishes.
Good luck.
