THE, a narrow strait, forming one of the communications between the Cattegat and the Baltic, and separating the Danish island of Zealand from the coast of Sweden. In the most extensive application of the term, the Sound is 66 miles long, from the Kullen in the N. to Falsterbo Point in the S., both on the Swedish coast; and its greatest breadth, opposite Copenhagen, is 17 miles; but the name is more properly restricted to the narrow portion between Elsinore and Helsingborg, where it is only 3 miles across. The Sound dues, formerly payable to the Danish crown by all vessels passing the strait, were abolished, 14th March 1857, by a treaty between Denmark and Great Britain, Austria, Belgium, France, Hanover, Mecklenburg-Schwerin, Oldenburg, the Netherlands, Prussia, Russia, Sweden, and Norway, and the Hanseatic cities of Bremen, Lubeck, and Hamburg. The contracting powers agreed to pay to Denmark a pecuniary compensation; and Denmark, on the other hand, consented to abolish the dues, and to continue the preservation of the lighthouses and superintendence of the pilotage of the Sound. The total amount of compensation granted to Denmark by this treaty was £3,386,258, of which £1,125,206 is from Great Britain. A separate treaty was concluded shortly after, between Denmark and the United States of America, for a similar purpose. The compensation in this case was fixed at £79,759. The navigation of the Sound is somewhat dangerous, as there are shoals and quicksands on each side of the channel.