"So if you were to dig a hole to the exact opposite side of the Earth, would you really end up in China? Not unless you live in certain parts of Chile or Argentina. In my case, I'd need to bring my swimming trunks, and so would almost all residents of the continental US, as we'd end up in the Indian Ocean between southern Africa and Australia...
...This map is handy for finding out a rough approximation of the antipodal (opposite) point of any place in the world, while this one is better for a bit more precision."
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