Look for public events at aquariums or zoos, and talk with the speakers or other professionals who attend! Often times, this is a great way to meet people in the field. Also look for volunteer opportunities related to your field of interest. Good luck!
Michael recommends the following next steps:
Texas A&M has a great job board with paying and volunteer jobs. Stop dodo has a lot of volunteer jobs around the world that will pay you a stipend or your housing.
Fisheries observer or protected species observer work is also a good option and only requires a B.S. and often opens the door to other work with state and government agencies.
So maybe, you can start volunteering on any marine reserve, and then return to see if they can give you a job.
Another way that I can advice, is to become friend of any teacher of your university related to the marine biology, and then start to help in any project of they, and then it also helps you getting experience that later, any work will request you.
Priscilla recommends the following next steps:
Find a university with a Marine Biologist program, preferably somewhere you are willing to move to. Look at their admission requirements and work towards fulfilling them. Hope this helps.
Glenn recommends the following next steps:
Marine biologists further specialize into their careers and I’m not sure what you want to study—you didn’t say freshwater or sea water or which particular animal you have an interest in. MBs are needed everywhere from state resource management departments (yes, even the state of Nebraska) to very remote islands on pearl farms and a myriad of roles in between. No matter where you live (yes, even Nebraska) there are aquariums, fisheries centers, state wildlife and conservation offices, and veterinarians who specialize in treating aquatic animals. Find a volunteer position and if any events are held, go and talk to the biologist giving the presentation. You will have a good reference and build your network, but do not let this come before your studies. You will have many people competing for a very limited number of graduate spots.
Be sure during your time as an undergrad, you study for the GRE and submit your application to your graduate school on time, every time. I am partial to the University of Texas A&M at Corpus Christi (have a good hurricane evacuation plan....just saying).