Danish Øresund
Almost tideless strait between Sjælland island, Denmark, and Skåne, Sweden, connecting the Kattegat Strait with the Baltic Sea .
It is one of the busiest sea lanes in the world, though ice sometimes impedes navigation in severe winters. Three large islands within it divide the waters into channels. The strait's principal ports are Copenhagen and Helsingør in Denmark and Malmö and Hälsingborg in Sweden.