The first thing to learn is if you have the legs as well as stomach for this type of work, especially if you aim to be at sea for lengthy periods of time. If you live near a port, get a part-time job on a sightseeing or fishing boat. This will give you the opportunity to experience what it's like to work while on a moving vessel. You will also have the opportunity to see what a ship captain does. See if you can set up a time to speak with the captain to ask questions about the job and find out what steps they took to get into the profession. You can also learn more about maritime professions through online exploration. One place to start is by visiting the Web site of the U.S. Department of Transportation's Maritime Administration (MARAD), which features information about the merchant marine and waterborne transportation, as well as a list of maritime colleges and academies.

Ship's captains operate and maintain nonmilitary vessels. Their main job is to ensure the safety of their crew, the passengers, and the goods and products that they are transporting on the ships. Typical tasks include supervising the work of crew members and officers, preparing budgets for the ship's maintenance and repairs, keeping records of the ship's activities and travels, overseeing the loading and unloading of passengers and cargo, and interacting with passengers. They may work on cruise ships, ferries, fishing boats, tugboats, freighters, or barges.

Captains work closely with ship's officers, pilots, sailors, deckhands, ship's engineers, and engine room crew. Those who command large deep-sea container ships oversee the transport of manufactured goods and refrigerated cargoes around the world. Captains also work on bulk carriers that transport heavy commodities, such as coal or iron ore, across oceans and the Great Lakes. Captains work on large and small tankers that move oil and other liquid products to different parts of the United States and to other countries. Captains of supply ships transport equipment and supplies to offshore oil and gas platforms. Cruise ship captains oversee large crews and many passengers and may travel for days or weeks. Ferry captains operate boats that carry passengers short distances.

The crew for most deep-sea merchant ships, large coastal ships, or Great Lakes merchant ships typically consists of a ship's captain, a chief engineer, three mates, three assistant engineers, and a number of sailors and marine oilers. Vessels that operate in harbors or rivers are usually smaller and require fewer crew members than merchant and coastal ships. The U.S. Coast Guard regulations determines the number of mariners required for ship's crews.