Why was he there at just the right time anyway? Was he doing some kind of spot check on the SWT, or perhaps going to the Southern Air Temple? Is it possible he just ran out of places to look for the Avatar, and decided "I know, I'll try the South Pole!" But we never really know why Zuko decided to go there. Does anyone have any ideas on this?
Ah! Serendipity! And how many waterbenders had been in the very same area where Aang's bubble was in 100 years? And I guess Azula can thank her lucky stars Katara didn't bloodbend her in that final battle?