After completing the task for Master Felix and after you have gone back to the ship to head for the next island (the one with the purple cloud above it), if you take the north-east path, you'll come to a wide circular area which shows on the map. You'll find a treasure chest that can be opened with the magic key. You'll get a suit of zombie mail. Whatever you do, DO NOT equip it! It's cursed! I made the mistake of putting it on Angelo and had to pay around 700 or 800 gold coins to lift the curse. So I'm advising you, DO NOT EQUIP THE ZOMBIE MAIL!!! (But it can still be sold at the nearest shop for a couple hundred gold coins.) Just thought I'd warn you all before you make the same mistake as I did. It's really not worth losing all that money.