Golden Sun: The Lost Age/Atteka Inlet
Get off your boat and climb down the ladder. Walk across the shallows to the shore. You'll see a random wing here, and something about a prophecy (oh no, not another one!).
Go west and up the slope. On the left-hand side of this next area is a ladder, which you can follow the path up to get a Vial from the chest. Anyway, leave Atteka Inlet and go all the way north to the giant crater. Enter Contigo, the village just next to it.