None. This achievement may be partially broken.
This achievement may not unlock despite performing the task correctly. Some people have had trouble with it, others (including myself) have had no problem earning this. I have confirmed that it will unlock without any kind of trickery or modification. Ragan651 (talk) 21:53, April 24, 2013 (UTC) (Lead Editor)
This only works on "round" maps, which includes all the basic map types. Fixed maps or regional maps that do not loop will not work.
To unlock Magellan, you must be the first person to travel around the world by boat on a global map.
Ferdinand Magellan was an explorer who was the first explorer to cross the Pacific Ocean from the Atlantic, and lead the first expedition to circle the entire globe. This achievement is named after him.