Treasure Isle

Treasure Isle is an optional dungeon-style location found way out near the top of the Great Eastern Sea in Golden Sun: The Lost Age. It is essentially two dungeons in a row, with one much harder and accessible much later than the other; the easier first part can be explored as soon as Felix gets the Grindstone and its Grind Psynergy in Lemuria. The later part can only be explored after the Reunion, when Isaac's party joins up with all their own Utility Psynergy items, including the Lifting Gem and its Lift Psynergy. Among the stronger equipment are the Iris Robe and the Fire Brand, and at the end of the dungeon is one of the most dangerous opponents in the entire series to battle, the Star Magician, who guards the Summon Tablet for the Azul Summon sequence.

Treasure Isle is initially filled with ancient pirate treasure. Just prior to the start of Golden Sun: The Lost Age, the pirate Briggs discovers the isle and loots whatever treasure he can, but due to a puzzle that blocks off non-Adepts without the ability to grind down giant spires of earth, a large portion of Treasure Isle's loot remains untouched.

Earlier portion
Once you have found the Grind Psynergy in Lemuria, sail up into the northeastern-most island on the world map, and go around into it counterclockwise to bypass the rocks that prevent your ship from being able to just go up straight into it. Disembark on the island's beach and enter the location. At the upper left part of the first cave-like screen, there are three open doorways lined in a row, with two of them near an earth pillar. The two cave doorways near earth pillars contain chests that are empty; Briggs and his pirates had previously looted Treasure Isle to a degree, but the leftmost door contains unopened chests containing 161 Coins and a Lucky Medal. Proceed to the more separated fourth cave doorway to the upper right to enter the next room.

You enter a watery room with hoppable platforms and no less than six chests to your left which, unfortunately, also had been looted by Briggs. When you hop straight up, though, you are forced to land on a red button that immediately makes four enormous earth spires rise straight out of the water, which would block you from going any further if you do not have the Grind Psynergy. If you do, you can use it on the giant earth spire to your right to return it into the water, and be able to hop right and enter the next room to the southeast. The dungeon from here on out is untouched by Briggs.

In the next watery room, hop your way down and right, and work your way counterclockwise to the area where there is an earth pillar bordering a red button. Do not move the earth pillar onto the red button; rather, move it down and left one space each so that it is positioned below the button. Retrace your steps until you are at the spot two tiles below where the earth pillar is now positioned, and cast the Move Psynergy to remotely move the pillar one tile up onto the red button. The giant earth spire in this room rises, but without trapping you behind it because you had the button pressed from the bottom part of the screen, so now you can climb up to the tightrope and proceed right and into the doorway at the upper right corner of the room.

In the third watery room, hop up twice to step onto another red button, which makes three giant earth spires rise out of the water. To both pass the area and collect its treasure, simply Grind the right earth spire and hop north beyond it. Climb up to a vertical tightrope and follow the elevated path south and west to reach a chest containing the Jester's Armlet. Return back down to below the tightrope, hop left, cast Move on the earth pillar to move it left into the hole, and hop your way north to the doorway at the top part of the screen.

In the next area, which is comprised of narrow, winding cave paths with a fork going up and down, take the lower fork and go to the west end of the screen, where there is a chest that reveals itself to be a Mimic when opened. It rewards you with a Power Bread when felled. Go south of where you fought the Mimic to exit out of a doorway leading back into the first watery room, hop down, move the earth pillar two spaces left into the hole, hop down once and left twice to get onto a small island with a pillar with a ladder on it, climb it, hop left across an elevated earth spire, and reach the six chests in the upper left part of the room. They contain a Rusty Axe that is reforged into the Viking Axe in Yallam, a Cookie, a Sylph Feather, a Star Dust, 911 Coins, and a Psy Crystal.

The earlier portion of the dungeon is considered complete once all of these chests are looted, but if you are playing this dungeon after Lemuria but before Isaac's party joins the team, you will not have the Psynergy needed to progress into the later, deeper, tougher portion of Treasure Isle, so you would have to cast Retreat now. Otherwise...

Later portion
Return to the branching cave-hallway room where you fought the Mimic, and take the fork up to enter the lower floor. A spherical boulder blocks your path into the rest of the first room of the lower floor, but once you cast the Lift Psynergy on it to bypass it, you can begin the second half properly and start fighting the far more powerful monsters down here. First, go west to find a chest containing a very powerful robe named the Iris Robe, then go down the narrow path below the chest and follow it to another Lift-able boulder at the left part of the screen. Past that is a doorway to the next room.

The next room, arguably the most noteworthy room in Treasure Isle outside of the last chamber, is a large puzzle room similar to the main puzzle room in Shaman Village Cave, with no less than six Lift-able boulders to carefully choose from to try to get three rewards: A chest, a Jupiter Djinni, and the exit to the next room. The room requires two visits to get all three, but the only boulder you would ever need to Lift in order to get both the chest and the Djinni is either the lower center one or the lower right one. Walk past it to reach and climb up the lone wall ladder near the center of the room, hop right, and go down the right tightrope to get to the chest containing the powerful Fire Brand. Hop back left, get to the second tightrope from the left, hop onto its top part, but instead of climbing across it, drop off it to the left so you can climb onto the leftmost tightrope and go down. Now you can battle the Djinni (which will not fly away from you as you approach, incidentally), and earn the Jupiter Djinni Gale. Exit back out of the bottom doorway to the room and reenter to perform a puzzle reset.

To get past the large Lift-able boulder room, Lift the lower left boulder, then Lift the upper left boulder. Hop right across the top portion of the room, then Lift the upper right boulder. Hop left to climb up the wall ladder at the center of the room, hop left, walk down across the second tightrope from the left, and hop right twice to climb down a ladder leading to the lower right corner of the screen. There is a doorway leading up and a doorway leading down, but the doorway leading down just leads back into the Iris room, while the doorway leading up connects to the dungeon's penultimate hallway.

In the narrow cave hallway beyond the Liftable boulder room, there is a fork branching between up and right, and ordinarily the fork up leads to a dead end, but it is possible for this fork to be extremely valuable: If Isaac's party joined without all seven of the original game's Venus Djinn for whatever reason, one of the missing Venus Djinn will be available again to collect at the end of this dead-end, without a fight. At any rate, take the right fork to reach the doorway at the top of the screen, and the last chamber of Treasure Isle is the site of the battle with the optional boss Star Magician. Easily the most tricky and strategic boss encounter in GBA Golden Sun games, the Star Magician will mount considerable resistance against your quest to collect the dungeon's ultimate reward that he stands in front of, the Azul Summon Tablet. Once you have collected the summon, cast Retreat to return to the entrance to the earlier part of Treasure Isle.

Collectibles
Treasure Isle has loads of treasure chests, but all of the ones that could be reached from as soon as the location can be accessed are empty because they have already been looted by Briggs and his pirate crew prior to the beginning of The Lost Age. The earlier, easier part of the dungeon, explorable with Grind, has seven chests that the pirates were unable to loot themselves:

911 Coins: In the bottom left of the six chests in the first "main" room. Cookie: In the bottom right of the six chests in the first "main" room. Psy Crystal: In the bottom center of the six chests in the first "main" room. Rusty Axe: In the top center of the six chests in the first "main" room. Is reforged into the Viking Axe at Yallam. Star Dust: In the top right of the six chests in the first "main" room. Sylph Feather: In the top left of the six chests in the first "main" room.

Jester's Armlet: In the lone chest in one watery room to the east with raisable Grindable pillars. Reached by raising all the pillars in the room, and then casting Grind on the rightmost pillar.

Whereas these collectibles repose in the deeper, more challenging portion explorable only with the Lift Psynergy gained late in the game:

Azul: This Summon tablet lies at the final room of the dungeon, guarded by the optional boss Star Magician. Essentially, the dungeon's "main" goal and reward, following one of the main optional "superboss" battles of the game.

Gale: In the room with Lift-able boulders in the style of a similar puzzle in Shaman Village Cave. Both this Djinni and the chest in this room can be collected just by Lifting the lower center boulder. Gale must be battled to be acquired. A Venus Djinni may be found here near the entrance to the final room, depending on whether Isaac's party has joined Felix with less than all 7 of the first Golden Sun game's Venus Djinn in his party's inventory. This will be one of the missing Venus Djinn from the first game making a reappearance for the party in The Lost Age to collect. You do not need to engage it in combat in order to obtain it.

Fire Brand: In the chest in the room with Lift-able boulders in the style of a similar puzzle in Shaman Village Cave. Both this chest and the Jupiter Djinni in this room can by collected just by Lifting the lower center boulder. Iris Robe: In the chest in the room where you first enter the deeper part of the dungeon.