I was looking for this item myself and noticed it's location wasn't listed. I remembered getting this item years ago when I played Ys on the Turbo. I also remembered it was in the Ice Park. but not where. Anyway, I did find it and thought I would share it's location for anyone else who might be looking for it. It is indeed in the Ice Park, East section actually. You have to get the Misty Ice Drops first and after you have frozen the bridge in the cavern, you can reach the cape. After you have frozen the bridge and exited the cavern, go south down the first steps you see. Stop and go to your right, there is a secret passage on the right side of the steps. The cape is inside the small cave here in a chest. Although I could barely see it, there is some kind of mark/shadow on the ground where the secret passage is.