Östhammar is a municipality in eastern Uppsala County in Sweden. While the Östhammar town itself has a population of 4,500, the municipality has more than 20,000 permanent residents, and several more during summer.
Östhammar is famous for the iron industry founded by the Walloons in the 17th century.
- Dannemora, a mill town
- Öregrund, a port
- Gräsö, an island
- Forsmark nuclear power station
- Vallonbruken: The Walloon metal industry