If you are looking for a new source of income in Final Fantasy XIV, then treasure maps are for you. These treasure maps can give you access (via a portal) to a secret dungeon in which you can get many items & very often enough gil to make the story quests jealous.
To start the treasure hunt you must first reach level 36 and complete the quest "Treasures and Tribulations" available from H'loonh in Eastern Noscea.
Once this quest is completed you can start collecting and deciphering your maps. There are many types of maps but the most profitable currently are:
- Glaucus Hide Cards (Group Level 80)
- Gazelle Hide Cards (Group Level 70)
You can collect a map every 18 hours at any gathering point of this level.
Once opened you will have to locate the chest, you will have to go to the point and use the excavation action. Monsters will then appear and you will only be able to open the chest once the waves have been defeated.
Once opened the chest may or may not open a portal for you. When a portal is open you will be able to progress through the floors towards better rewards. The goal is not to spoil you too much inside the portals which are a mini-game in themselves.