Here's a map and method to find out what's on the opposite side of the world at a particular location.
Any point on the surface of a sphere, in this case the Earth, that lies diametrically opposite from a given point on the same surface, so that a line drawn between the two points through the center of the sphere forms a true diameter (e.g. line through the Poles of a Sphere). The Antipodes islands of New Zealand, in the South Pacific, are named after this geodetic feature because of there near opposite location to London.
