"Compasses point to a magnetic north near Prince of Wales Island above Canada, but most people navigate using charts that call the North Pole 'true north.' Depending on where a ship or plane is, the compass variation between the two can be significant. In the Azores, for instance, the difference between 'true' and 'magnetic' north is 20 percent. Just off the coast of Florida, the variation is nil in some places where the two are in perfect alignment. Oddly enough, the only other place this alignment occurs is in the Pacific Ocean east of Japan, an area that sailors—perhaps not coincidentally—call the 'Devil Sea' for its high incidence of disappearing ships. Some scientists say that in both these areas compass deviation may cause some people to wander off course and into trouble."
—Brian Hicks, Ghost Ship: The Mysterious True Story of the Mary Celeste and Her Missing Crew (NY: Ballantine Books, 2004), 221