Treasure Isle

From Golden Sun - Wiki on Neoseeker

Treasure Isle, like it's name suggests, it fill to the brim with treasure chests. However, the first few treasure chests you see have nothing in them. Why is that? Because they are easy to get to. However, once you have left Lemuria with the Grind Stone, you will be able to stop those spikes that appear whenever you jump across to the platforms. This opens up a lot of treasure to be had. In this dungeon lies some strong armor and some powerful weapons and even a very tricky boss; the Star Magician.