High Quality Content by WIKIPEDIA articles! The Battle of Svensksund (Finnish: Ruotsinsalmi, Russian: Rochensalm) was a naval battle fought in the Gulf of Finland outside the present day city of Kotka on 9 July 1790. The Swedish naval forces dealt the Russian fleet a devastating defeat that resulted in an end to the Russo-Swedish War of 1788–90. The victory has been named the biggest Swedish naval victory of all time.