Visualisation of Global Cargo Ships
This delightful presentation of the movement of ships around the world is well worth studying. It is NASA data from 2012. Each ship at sea is given a dot and GPS tracked as it moves from one port to another. The color of the dot identifies tankers, container ships, etc.
You can choose where to look more closely and magnify that part of the Earth. Learn to play with the very intuitive and simple controls and you can choose to follow only tankers or container ships. You can zoom in on crowded points like the Suez Canal or Gibraltar.
It is well worth exploring for a while. Have fun.