Karlskrona is a city of about 66 000 people and spread our over 30 islands in the Blekinge Archipelago. It was founded in 1680 when the Royal Swedish Navy was relocated from Stockholm to Trossö Island. Sweden's navy dominated the Baltic Sea, but it needed a better and more southerly location in order to ward of Denmark. Denmark had taken over parts of Sweden during the Torstenson War (1643-1645). Moving south also helped it avoid getting stuck in ice, which was common in Stockholm. The city is named in honour of King Karl XI and means "Karl's Crown." Today the Naval Port is a UNESCO World Heritage Site.