Required: Wire Rod

Use your Wire Rod to cross to the mountain range in the northeast corner of the world map. Instead of moving west to Joe's Shack (the Inn), move east. Use the Wire Rod to cross the small river and walk along the cliff fast heading east. You'll come to an area with some enemies and a ridged northern cliff face. Examine this cliff face on your minimap. Between two of the ridges you should be able to make out a red pixel in the second nook from the right.

Stand on the red pixel to warp to a new location. Here you'll find a chest with the Anchor Rod. You can use this to access previously out of reach areas -- like the upper right hand corner of the map!