Kärdla is the only real town on Hiiumaa, Estonia's second-largest island. It is small and quiet — more a large village than a city — with a handful of shops, a couple of cafes, and a pretty town park built around the ruins of an old cloth factory.
Few visitors realise that Kärdla sits inside a meteorite impact crater — a 4-kilometre-wide bowl formed some 455 million years ago. The crater is not obvious from the street, but the Hiiumaa Museum has a good display on its discovery and geology.
The town makes a convenient base for exploring Hiiumaa. The island is known for its lighthouses, juniper-covered coastal heaths, and an unhurried pace that feels remote even by Estonian standards. The Tareste conservation area just outside town preserves a stretch of these characteristic juniper heaths. The Kõpu Lighthouse on the western tip is one of the oldest continuously operating lighthouses in the world.