Kärdla is the largest town on the Estonian island of Hiiumaa and the capital of Hiiu County. Kärdla is located on the north-eastern coast of Hiiumaa, by the Gulf of Tareste (Estonian: Tareste laht, original Swedish: Tarrasviken). Southeast of the town is the Kärdla meteorite crater, which is 455 million years old. Several small rivers flow through the town. There are also artesian wells in Kärdla.
Kärdla was first mentioned in 1564 as a village inhabited by Swedes. Its growth was greatly influenced by the cloth factory founded in 1830. A port was built in 1849. Both the port and the factory were destroyed in World War II. Kärdla officially became a borough in 1920 and a town in 1938.