We combine tracking data from the publicly available automatic identification system (AIS) and integrate that with information acquired through vessel monitoring systems that are operated by governments and made available to us through partnerships that we secure. Both AIS and VMS combine global positioning with a transmitter to regularly broadcast vessel location. After harvesting and preprocessing each dataset, we apply a variety of algorithms and machine learning models to monitor the activity of fishing vessels at sea. In addition to the act of fishing, vessels engage in numerous behaviors—such as transshipment and visiting ports of call—that affect the sustainability, traceability and transparency of the seafood supply chain. We identify these events in various ways and share them on our map in order to provide a more comprehensive picture of global commercial fishing activity.