Réponse :
We can see that the boat leaves from Portsmouth, in England, to then make two stops: The first one is at Rio de Janeiro, in South Africa. The second stop that the boat will make is at Cape Town, in Africa. Then, the boat will finally arrive at its final destination, Sydney, in Australia.
The title "Down Under" is probably due to the fact that the boat is going down, it's going to the bottom of the map, and I think that's why its called "The long journey Down Under"