There are several kinds of accommodation close by.
You could stay at Hotell Fars Hatt (+46-303-10970; www.farshatt.se; SEK 640-830) where the party will be held. For Friday and Saturday there are 20 pre-booked rooms that will be held until July 1st. When booking this accommodation, quote 'Malin Pacsay'.
The camping and hostel (+46-303-18900; www.kungalvsvandrarhem.se; SEK 130/185) are located opposite the fortress Bohus Fästning.
There is also a bed & breakfast at Kanarpsgården (+46-3003-206200; www.nordiska.fhsk.se; SEK 350-590).
Booking a little stuga (holiday home) is also possible: Contact the Tourist office in Kungälv for information and bookings (+46-303-992-02; www.kungalv.se/turism).
