You’re back in the Academy. Talk to Hugo; he’ll talk to you about the Wishing Well. That’s where you throw Wish Stones that you find while exploring the world. You probably have a decent collection of them by now. See what you can get by throwing them into the Wishing Well!
You can get Hats, Soul Gems, Winged Sapphires, Kaos Diaries, Skystones, and other cool goodies from the well. Enjoy your prizes, and then talk to Flynn to head to the Monstrous Isles.