To use a treasure map, go to Items in the menu and choose
Treasure Maps. Then select the map and choose "go treasure-hunting."
If you are outside of a town, you will see the treasure map in the top
screen.
For help finding the location, use the
Grotto Map Hex Code Finder.
When you get to the spot marked with an X on the map, a ! will appear and you
can press A to make the grotto entrance appear.
Use the Grotto Map Viewer to see the full
map of the grotto.