A correction in The New York Times, April 10, 2016:

An article on March 20 about wave piloting in the Marshall Islands misstated the number of possible paths that could be navigated without instruments among the 34 islands and atolls of the Marshall Islands. It is 561, not a trillion trillion. (source)

Image: “A Micronesian navigational chart from the Marshall Islands, made of wood, sennit fiber and cowrie shells.” (source)