The MarineTraffic service makes use of AIS tracking technology to provide information about the identification, course, speed and current location of vessels. From there, locations can be overlaid onto Google Maps and, as a result, users can use the service to track the movements of ships and other vessels in real-time.
Additionally, some information surrounding ship locations is self-reported from those aboard. This information is then used to provide a more accurate and up-to-date live map of vessel locations.