Salmon Reds

The Salmon Reds (サーモンレッド) are large scale boats stationed in twelve places on Liberal Arts City's coast in case of an emergency evacuation.

Principles
They are described as being 200 meter class highly buoyant ships that a single one is capable of carrying 80,000 people. Each person person on board only has about a sleeping bag’s worth of space and apparently each of those spaces can function as an independent boat by way of holding a large number of tiny boats with the people on them made them look like salmons holding their roe. No specialized knowledge of the boats is needed to use the Salmon Reds sense they are GPS controlled and will automatically avoid reefs and other boats as they head for the American mainland. However, all that is just to allow them to carry out their function as boats. They cannot carry out the precise movements needed to dock, so a rescue team would have to save the people on board.

Since the ocean around Liberal Arts City is still maintained as the environment of 50 years into the future needed for filming the movie, so something like a net is surrounding the area to prevent fish and other creatures in the ocean from coming and going. However, when the Salmon Reds start moving, that net needs to be torn away. That may be one of the reasons the ships are almost never used, the other being that the Salmon Reds are kept where they are conducting their secret research. In order to appear to be a safe and comfortable movie city, they do not want to let their emergency boats be seen if they can help it.