Now any city can be a harbor city, say researchers at the Korean Advanced Institute of Science and Technology.
Institute President Suh Nam-pyo says he got the idea for the mobile harbor on a trip to Singapore.
"When we got near a harbor there, I saw all these ships waiting out there, I am guessing, waiting their turns to load and unload the cargo," he noted. "I said, 'Why do the ships come into the harbor? Why not have the harbor go out there and bring the goods in?'"
Researchers describe the mobile harbor as a lean, light system for unloading container ships even if the coastal area is too shallow for them to dock.
Specially designed cargo barges would head out to meet and unload gigantic container ships along any coastline. The vessels will have the advantage of being able to navigate shallow water and squeeze through rivers.
At the shore, they then will offload onto specially designed receiving platforms.
It sounds easy, but senior engineer Gwak Byung-man admits there are daunting technical challenges.
"The ocean is always rippling, and especially for smaller boats, it is extremely hard to load and unload containers in a stable way," he explained. "So our main challenges are: how do we stabilize the vessel itself in all those waves? And second: how do we stabilize the loading equipment aboard the vessel?"
An institute exhibition displays the project's obsession with stability. Pulleys, axles and shock absorbers document researchers' efforts to deal with the rolling waves.
Ahn Choong Sung, head of the company that will sell the mobile harbor vessels, says success is not far off.
He is marketing the concept to small developing markets that do not have deep-water ports, or the budgets to engineer them. It could save many cities the cost of shipping goods by road from larger ports.
"We're used to shipping goods to places like New York or New Jersey, and then moving on to South America," he said. "With the mobile harbor, we can bring goods to other places directly. It will expand the container shipping market and also help the environment. After all, using cars to move goods causes a lot of carbon air pollution and traffic jams."
The developers of mobile harbor say the system also will boost anti-terror efforts, by keeping container ships with potentially dangerous cargo away from populated areas.