The Keys to the Kingdom: Drowned Wednesday by Garth Nix

Drowned Wednesday is the third book in the series of The Keys to the Kingdom. Arthur is in a hospital because of his previous journey with Tuesday and has gotten a invitation to lunch with Wednesday. Arthur's friend Leaf is transported with him to the Border sea a ocean in the house that Wednesday is in charge of. Arthur must figure out how to survive in the border seas with fearsome pirates  with Leaf and find Wednesday and get the key. This is a good book because it is a exciting adventures at the center of the universe. I liked it also because of the characters like Arthur who is brave and some of the pirates are cool too.