Sakura and the Many-Layered Sea: A Tale of Density and Buoyancy

Once upon a time, on the oily shores of the Many-Layered Sea, there lived a girl named Sakura. You might think that an oily sea sounds worrisome, as if it were the result of a spill or disaster, but this was simply how the sea was. The top-most layer was a quarter-mile thick of oil and plentiful with swarms of oil eels. Which were delicious.