You have known all your life that you want to be a marine biologist. Go to a local day care or summer day camp. Park ranger, a national park or summer overnight camp. Writer, your local newspaper, library, or historical area. If you're not sure what you want to do, find something that interests you and give it a try.
Transportation is an important factor in finding a job.
Look close to home if you have doubts that you can find your way back and forth every day. If you have to get a ride from someone, remember to show your appreciation by offering gas money or something in return for their time. If you want a job that takes you seriously, walking around an amusement park in a goofy costume would probably not fulfill that wish. On the flip side, if you want your summer to be all fun, working indoors in an office environment probably won't make you happy. Look to the places that you and your friends like to hang out at.