There are two optional dungeons and seven optional bosses. You have to beat the game and load your cleared save file to access these optional bosses and dungeons. None of these optional bosses or dungeons have any story or dialogue at all; they’re just there for you to fight.
Oldtymer posted a list, which I’ll link to below. The list thread does give a few details about the bosses – their HP, weaknesses, rewards, and estimated difficulty.
I’ll give a quick summary of where to find the bosses on the list, without any other details.
There are three “seabed cave” optional bosses. You have to use the submarine to reach them. The cave entrances are all very obvious and easy to find, just search the underwater map.
There’s a boss in the ice cave on the snowy island, on the main world map (not the underwater map or the sky map).
There’s a boss in the Valley of Flowers. The Valley of Flowers is on the main world map, on a small island with a few plant life squares. The Valley of Flowers is not a full-sized dungeon; it’s just a clearing with the boss.
There’s an optional dungeon with an optional boss near the Dwarven Hamlet.
There’s an optional dungeon with an optional boss in the sky map. It’s easy to find, just fly around on the airship and you’ll stumble across it. This optional boss is the only one that can be fought repeatedly; if you beat him, leave the dungeon, and return, he’ll come back.
Favorite RPG of all time: Journey to Kreisia (by Exe-Create)
2 users thanked author for this post.