Lars’s tanker was built to do a very special kind of job. So were many other kinds of ships. Look at the Seatrain, which carries fully loaded freight cars—a hundred of them at a time.

To load a Seatrain, the railroad locomotive pushes a string of cars out onto a long pier. A derrick lifts the cars up one by one, swings them over an open hatch, and lowers them neatly onto tracks in the ship’s hold. After the holds are filled, there’s still room for more cars on the main deck outside.

It seems queer for trains to travel by ship, but sometimes that’s the best way to send cargo. Freight cars can be filled with sugar on the island of Cuba and brought across the water to the United States, without any extra loading and unloading. It’s often cheaper for freight cars to go by ship than by rail from New York to Savannah or New Orleans or Texas City.