New Scientist magazine has a feature called "The last word", in which readers' questions are answered by other readers.

Recently one reader's question asked what point on earth was farthest from the nearest sea, meaning farthest from any inlet of the world ocean. Rivers don't count, just seas, connected to the world ocean and subject to tides of the whole sea, not just seiches.

A reply was published, calling this point the "continental pole of inaccessibility (CPI)", that said the question was raised in the 1960's when builders of submarine-mounted nuclear missiles wanted to tout an ability to target any point on land from a body of water accessible to the sub fleet.

The reply stated that the point is at 46°17'N, 86°40'E, in northwest China near the Russian border, and went on to say that the nearest arm of the sea was 2848 km away at Tianjin on the Yellow Sea. It stated further, that the sub proponents neglected to mention in promotional literature that as the rockets had barely enough range to cover this distance, that "to strike the pole [of inaccessibility] a large nuclear-powered submarine would practically have to visit Tianjin docks."

What's wrong with that reply to the reader's question?

(In reply to re(2): Somewhat confused by Charlie)

I essence what I have probably been saying too poorly is that the given locationto be farthest from Tianjin must also be farthest from the ocean by at least one other place but most likely two. Which of the other locations I have nominated really is insignificant, it just means that while being farthest from Tianjin it is also at its farthest point from at least two of my nominations, that distance being radial.

If in fact the given location is true then one could never draw a larger circle on a land mass on Earth with 3 ocean/sea locations equidistant from its centre and not impinge on the sea (unless that point was a coastal location on the circle's circumference).

I don't think I can do much better than that Charlie.

Posted by brianjn on 2008-05-15 19:56:34