User blog comment:AYET/Mihawk - to the NW and back.../@comment-162.53.2.115-20120222071828

Mihawk takes his sword.

Send out a circular slash against the reverse mountain.

A hole is formed.

Mihawk passed through the Grand Line to Blue sea. END OF STORY.

Since he is not poor in direction he used that path to travese between GL and Blue Seas.