My friend Ginge, who is even now attempting to climb the highest
mountain in every country in Africa, ran into a peculiar hazard of
the Africa/Asia divide - the highest point in Egypt lies in Sinai,
which many folk consider to be in Asia. But Egypt is an African
country, and therefore must have its highest point climbed. So does
he climb the highest point of Egypt *in Africa*, or does he leave
Africa to climb the highest point in Egypt?
He has already knocked off the national highest points of Europe, and
had similar philosophical problems there:
a) Is Russia in Europe or Asia? Fortunately the highest point
of "European" Russia is also the highest point in Russia, so he
climbed it.
b) The Transcaucasia debate already alluded to - he ended up doing
Georgia, Armenia and Azerbaijan to satisfy the Guinness folk. He was
happy to draw the line at the Caucasus ridge-line, but they weren't.
c) Does Turkey's little footprint in Europe qualify it as European?
(It certainly likes to be European for soccer matches and the
Eurovision Song Contest!) Again, did he climb the piddling little
hill that is European Turkey's highest point, or venture into Asia
for Ararat? (He climbed Ararat.)

Personally, I think continental divides are physical geographical
concepts, and ought to follow physical geography, rather than
political geography (and this is at the core of all Ginge's
difficulties). So mountain ranges are good, and the narrowest points
of isthmuses also seem good. But do I want to draw a straight line at
the narrowest point? Doesn't feel right. Some riverine route from one
coast to the other feels more "physical" to me, so I imagine I might
end up snaking along the canal routes, like Michael (do the canals
take the narrowest+lowest line? I don't know).
And I haven't the foggiest notion what to do with the Europe/Asia
divide south of the Urals and north of the Caspian. Does anyone else?

Grant