As you progress through Adventure Mode, you'll be able to unlock brand new maps to play on. These maps will contain new missions and new rewards, including weapon upgrades for all characters. New maps unlock when specific missions are cleared.

Map	How to unlock
Master Quest Map	Clear Great Sea mission C-9, "Final Battle! Defeat the Demon King of the castle!"
Rewards Map	Complete any of the Golden Skulltula pictures. (New missions unlock within for each picture completed)
Termina Map	Clear Master Quest Adventure Battle mission "Defeat the Demon King" on space A-1.
The Great Sea Map	Clear Adventure Quest mission "Defeat the Dark Ruler" on space A-6.
Twilight Map	Clear Master Quest Adventure Battle mission "Defeat the Demon King" on space A-1.