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 27-29, 2021. 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.