Urzai AU - While on a ship with the kids, a huge storm hits and the fire family’s ship is destroyed, leaving the family separated. Ozai and Ursa, having survived the storm together, wash up on the shores of the South Pole with no memory of who they are or how they got there.
Avatar au: for whatever reason (Ursa takes off with Zuko to find somewhere safe, Iroh takes him around the world, he gets banished to the pole, etc) Zuko comes to hang out at the South Pole and becomes unlikely friends with the water kids. It obviously starts out rocky, but gets there eventually.
The ice breaker "City of New York" sails from New York Harbor, September 6, 1928, captained by Commander Richard Byrd, at the start of its 13,000 mile voyage to Antarctica.