Originally Posted by
kyushuman
I read on one blog about this award that it's only valid for a round-trip routing (begin and end in the same city or at least same country).
But reading the whole intro/wiki, that's not mentioned.
Can I do, for example:
1) Start in Asia, end in South America? (extended one-way with 16 segments along the way)
2) Start at JFK, end at LAX? (almost around the world)
Thanks, and feel free to point me to where it mention this if I'm too dense to find it myself.

There is no such roundtrip requirement for the explorer award. You can have a one-way trip that starts in one side of the earth and ends in another side, subjected to the stopover/connection limitations as posted on this thread.