Treasure Island Walkthrough - Golden Sun: The Lost Age
Treasure Island is a dungeon which you can access early on in the game but you can't complete it until you've gotten both the Grind and Lift Psynergy. I personally prefer to wait until Isaac joins the team and you get the Lift Psynergy to complete the dungeon that way you can do it all in one go... However you could come here after getting Grind and get some items then come back later.
You can find Treasure Island in the northern part of the east sea, if you need help locating it check out the Golden Sun: The Lost Age Map that I have been showing. When you first enter Treasure Island go left and into the left doorway to find two chests, one has 161 Coins and the other has Lucky Medal. The other two rooms have chests too but they're all empty.
Go north into the next room and ignore all the chests, they're empty. When you step on the switch here you'll cause some rocks to rise up out of the water. Use your Grind Psynergy on them to lower them back down - we'll be doing this a few times during the dungeon. Exit this room to the east by using Grind on the rock.
Tip: Don't use Grind on the northern rock right now and if you do reset the room; we need it up for later.
In the next room you will have to circle around the enclosure with the pillar and go into it. Then you'll want to push the pillar near the button but not overtop of it, like shown in my screenshot below. You'll need to push the pillar onto the button using Move while standing outside of the enclosure - when we do it like this it allows us to cross to a new area.
Position the pillar near the button then use Move on it from the outside
After you are outside of the enclosure, push the pillar overtop the button using Move and then climb across the tight rope to a new room. In the next room you'll be forced to hit a button that raises up the pillars up, you'll want to Grind down the pillar on the right first. Follow the linear path around the room to reach the chest with a Jester's Armlet inside of it.
Backtrack a little bit and use Move on the pillar - jump across and push it again. We can now exit this room to the north, this will put us in a long twisty hallway. The chest you see in here is a Mimic and it will drop a Power Bread when defeated. You have two exits in this area, the northern exit takes you deeper into the dungeon. The southern exit takes you to the first room of the dungeon and 6 chests with items. Assuming that you didn't use Grind on the pillar to the north at the start of the dungeon - you'll be able to collect these chests. If you did use Grind on it, raise the pillars again then retrace your steps.
Southern Exit (6 Chests): 911 Coins, Cookie, Star Dust, Psy Crystal, Rusty Axe (Viking Axe) and a Sylph Feather
If you didn't use Grind on the northern pillar at the start of the dungeon then you can climb across to the chests now
At this point in time you can't go any further in the dungeon until you get the Lift Psynergy. The path to the north is blocked by a boulder and you need Lift to bypass it.
After Getting Lift Psynergy
Later on in the game when you advance far enough Isaac and his comrades will join your party. He will automatically come with the Lift Psynergy since that is a mandatory Psynergy for beating the game. Use Lift on the boulder and collect the Iris Robe from the chest in the west. From here you'll want to go south into the room with the next Djinni, Gale. Lift the boulder in the center to easily reach Gale and capture him.
You'll want to collect the Fire Brand from the chest on the right too before you reset the room. After you've reset the room you'll want to use Lift on the left boulder, the one above that and also the boulder in the northeast. Use my picture below if you need to see which boulders I lifted on the screen.
Basically the logic here is you'll run up the path on the left, skip the boulder in the middle and Lift the one in the northeast. Go south of this boulder and jump over to the middle island in the room. This is where you see me standing below and the same boulders have been lifted.
From where you see me standing in the picture above you'll want to climb up and jump around the plateaus above so that you can navigate to the climbable wall in the bottom right. From here you can climb down to two exits, go south first to push the pillar over and create a shortcut. Next you'll want to go north where you'll find another Djinni if you aren't playing a linked game or your linked game didn't have all the Djinni. Check out my Djinni Locations (Part 5) for more details about this, specifically the section at the bottom.
Just north of where that Djinni is found you'll find a doorway which leads you to the final room of this dungeon. The boss of this dungeon is Star Magician and his Balls. My advice for this fight is to take out the Refresh and Guardian Balls immediately and try to do as much AoE damage as possible.
When the fight is over inspect the tablet to learn the Azul summon. This summon costs 4 Mercury and 3 Venus Djinn. Once you get this summon you're free to use Retreat and leave the dungeon.
Return to Golden Sun: The Lost Age - Walkthrough Chapter 11