Wacken Open Air is a heavy metal music festival, held annually since 1989 on the first weekend of August in the village of Wacken in Schleswig-Holstein, Germany. Almost all styles and subgenres of hard rock and metal are represented and hosted. It is now one of the largest heavy metal festivals in the world and one of the largest open-air festivals in Germany. Between 2011 and 2018, the number of attendees was around 85,000, 75,000 of whom were paying visitors. Due to the COVID-19 pandemic, there were no 2020 and 2021 editions of Wacken Open Air.

Schleswig-Holstein is the northernmost of the 16 states of Germany, comprising most of the historical Duchy of Holstein and the southern part of the former Duchy of Schleswig. Its capital city is Kiel; other notable cities are Lübeck and Flensburg. It covers an area of 15,763 km2 (6,086 sq mi), making it the 5th smallest German federal state by area.