Dynamo Open Air is a festival in the Netherlands held (almost) every year between 1986 and 2005. It was reborn in 2008 as Dynamo Outdoor and in 2015 as Dynamo Metal Fest.

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Originally held to celebrate the fifth anniversary of the Dynamo rock club in Eindhoven, it grew from 5,000 people in the Dynamo parking lot up to 118,000 attendees in 1995. Until this day, the 1995 edition still is the largest multi-day open air festival ever held in the Netherlands. This caused too much pressure on the Dutch infrastructure and the festival had to shrink to a maximum of 60,000 visitors for 1996. From there it went downhill, mostly because the festival could not find a permanent venue. In 1999 Dynamo Open Air was held on a former rubbish dump in Mierlo, and the following year it went to the Goffertpark in Nijmegen. That was the first time DOA was held outside the province of North Brabant, and it was the first time in years that the festival had to shrink down to only one day. The previous years it had always been a two- or three-day festival.

In 2001, the organisation thought they had found a site where the festival could return on a yearly basis, near the town of Lichtenvoorde. However, the threat of foot-and-mouth disease caused trouble, and Dynamo Open Air had to be cancelled. In 2002 it returned, at the site of the Bospop festival, but 2003 was another year without a Dynamo festival, because it would violate a recently passed law about animal protection during breeding season. For 2004, the festival returned to Nijmegen, at the same location where it took place in 2000. In 2005, the festival used the site of the Dauwpop festival, and the reunited Anthrax headlined the stage.

In an attempt to revitalise the festival, the current organization of the Dynamo youth center decided to change the festival's name from Dynamo Open Air to Dynamo Outdoor. In 2008, the first Dynamo Outdoor festival was held in the centre of Eindhoven, with bands such as Mad Sin, Anathema and Born From Pain performing. The festival was once again held in Eindhoven in the following year, with Destine, Stahlzeit, Asphyx, Textures, The Butcher and Municipal Waste on the bill.

The revival of the festival occurred with a new name as Dynamo Metal Fest, which has taken place every year since 2015. The festival had taken place traditionally on the second or third Saturday in July from 2015 to 2018; for the 2019 edition, it was converted into a two-day festival. After the 2020 edition was cancelled because of the COVID-19 pandemic, Dynamo Metal Fest was scheduled to return in August 2021, however again cancelled due to the COVID-19 pandemic.^[1] The Dynamo Metal Fest was again held in August 2022.