There and Back Again

Age 11 to 14 Challenge Level:

Bilbo decides to leave his hobbit-hole and go on an adventure. He walks 100 miles South, then 100 miles East, then finally 100 miles North, at which point he is surprised to find that he has arrived back home!

Many people would think that because of this Bilbo must live at the North Pole.
However, Bilbo doesn't live at the North Pole!

Can you describe where you think his home might be?
Have you found all the possible locations?