Thialf is an arena in Heerenveen, Netherlands, primarily used for speedskating and ice hockey. Thialf, named after Thor's servant Thialfi who had to race a giant, opened in 1967 as an outdoor rink. The roofed stadium, which seats 12,500 people, opened on 17 November 1986, about a year after Sportforum Hohenschönhausen in Berlin, which was the first 400m indoor speed skating oval in the world. Thanks to the indoor conditions, allowing climate control, almost all world speed skating records were broken at Thialf in the first season. Since 1988 it has been overtaken as the "fastest ice in the world" by the high-altitude indoor rinks in Calgary and Salt Lake City, which have the additional benefit of low air pressure.
Every year there are main skating events like the world championships. The world famous Trance Energy dance music event was held in the Thialf 3 times. In 2000 and during the second TE events in 2001 and 2002.