Sluis is a town and municipality located in the west of Zeelandic Flanders, in the south-western Dutch province of Zeeland.

Zeeland is the westernmost and least populous province of the Netherlands. The province, located in the southwest of the country, borders North Brabant to the east, South Holland to the north, as well as the country of Belgium to the south and west. It consists of a number of islands and peninsulas and a strip bordering the Flemish provinces of East and West Flanders. Its capital is Middelburg with a population of 48,544 as of November 2019, although the largest municipality in Zeeland is Terneuzen. Zeeland has two seaports: Vlissingen and Terneuzen. Its area is 2,933 square kilometres (1,132 sq mi), of which 1,154 square kilometres (446 sq mi) is water; it had a population of about 391,000 as of January 2023.