Porthaven itself is a poor village by the sea. The inhabitants of Porthaven include the unnamed girl who was given a luck spell for her father's boat to protect him from rough seas by Michael Fisher and the sea captain who wanted a wind spell. Location's include the quay, and Michael Fisher's old house which he was kicked out of because he couldn't pay the rent.
The Porthaven Marshes are where Howl caught a falling star as a child, and where Sophie and Michael later attempted to catch a falling star with the aid of the Seven-League Boots.
Before the beginning of the book, Michael Fisher was kicked out of his house by his landlord because he couldn't pay the rent. He slept on Howl's doorstep that night. Howl made him his apprentice the next day after he told Michael to wait there. The interior of Howl's Castle is really his house in Porthaven. As mentioned above, Sophie and Michael attempt to catch a falling star on the Porthaven Marshes using the Seven-League Boots. Porthaven is also the location of a duel fought between Howl and the Witch of the Waste, after which he moves Calcifer to the hat shop in Market Chipping in order to escape.
Porthaven is where the army of Ingary set out from and return to after being defeated. The Porthaven Marshes and the garden at the edge of the Waste are merged into Howl's Secret Garden.