Mysteryland is the leading electronic dance music festival in the Netherlands, organized by the Netherlands-based promoter ID&T. Being the first of its kind in the country when it was established, its organizers have billed the event as the oldest dance music festival in the Netherlands. It has most recently been held at Haarlemmermeerse Bos in Haarlemmermeer; an exhibition ground that hosted the 2002 edition of the Dutch gardening festival Floriade. It is traditionally held on the final weekend of August; the next date is August 25-27, 2023. Since 2015, the festival has changed from a one-day to a three-day event with camping. Each year, more than 100.000 visitors from over 100 nationalities are welcomed at Mysteryland.

ID&T is a Dutch entertainment and medium enterprise that was founded in the early 1990s. Their event Thunderdome is named the oldest electronic festival in the Netherlands, with later events like Mysteryland, Trance Energy and Sensation. It operates many of the largest electronic dance music events in the world. They were also involved in the editions of Tomorrowland up until 2013.