Travel is really dependant on what type of marine life you are going to study. If you work in a lab, then obviously you will do very little travelling, if at all. If you get a job at the zoo or at an aquarium, the position will be based there, with perhaps the occasional need to travel for a research project. If you are researching the migration of whales or are doing deep sea research, then you can expect to be travelling and to be out at sea for extended periods of time.
A marine biologist is someone who is interested in learning and studying marine organisms and what their lives are like in their natural habitats.