Strömstad is a locality and the seat of Strömstad Municipality, Västra Götaland County, Sweden with 6,288 inhabitants in 2010. For historical reasons, Strömstad is called a city despite its small population. Strömstad became part of Sweden in 1658, as part of the Treaty of Roskilde, which transferred the Bohuslän province from Norway to Sweden. It achieved town status in 1676. Strömstad became an important sea-bathing and spa destination in the mid-19th century. The close proximity to Norway is evident throughout town, and cars and boats arrive daily from Norway. Despite its small size, Strömstad is a bustling town throughout the year due to its international ferry link to Sandefjord, Norway. This is particularly true for Easter (especially Maundy Thursday) and the months of June and July, when thousands of vacationing Norwegians are visiting Strömstad. Strömstad claims to have more summer sunshine days than any other town north of the Alps. Strömstad has numerous daily ferries departing and arriving from Sandefjord, Norway. It is also home to a domestic ferry connection to the Koster Islands, a nature preserve which is Sweden's westernmost populated islands. It is home to Sweden's largest deepwater harbor. History Originally, the province Bohuslän, where Strömstad is situated, was Norwegian territory, which was transferred to Sweden according to the Treaty of Roskilde in 1658. At Strömstad, there was a small fishing village known as Strömmen. The town got small privileges as a merchant town (köping) shortly thereafter, which seems to have made it expand, because it is documented to have gotten a charter in 1676 by King Charles XI of Sweden, although some documents show it was already considered a city in 1672. As it was the seat for a merchant navy, the coat of arms was designed with such a ship, and has remained that way even after the use of sailing ships was discontinued in the 19th century. The city was a seat for Sweden's warfare against the Dano-Norwegians, and more than once it was conquered and reconquered throughout the centuries. The warlike King Charles XII of Sweden, for instance, used it as his outpost for his campaign against Norway in 1716–1718. At the time it had a population of 300 inhabitants. But soon the fishing blossomed, and its population increased to 1,100 by 1805. The late 18th century also saw the spa and bathing attract visitors, a position it kept throughout the 19th century. In