The end of the world has a name and a train station. In Ushuaia, the southernmost city on the planet, Tierra del Fuego National Park descends from the lenga forests down to the Beagle Channel. You board the End of the World Train — the very one the prisoners of the old penitentiary once rode — sail among sea lions and penguins, and breathe air that tastes different. It's the last patch of land before Antarctica.