The ferry crossing from Helsingør to Helsingborg on the Swedish side is four kilometres and takes about 20 minutes — the shortest international sea crossing in Europe. Ferries run throughout the day and evening, making a combined Denmark-Sweden day trip easy. The crossing itself is worth doing for the view of Kronborg from the water, which is the perspective from which it would have appeared to every ship approaching through the Sound.
Helsingborg has its own castle ruin (Kärnan tower), a pleasant old town, and good seafood restaurants. The combination of both sides of the Øresund makes for a full day out from Copenhagen, and is a good way to experience the Øresund region that the 2001 bridge further south partly displaced.