The North Sea Jazz Festival, Den Haag, The Netherlands. The North Sea Jazz Festival is the largest indoor music festival in the world, known globally as the event where the past, present and future of jazz are featured within three days. Next to a firm base of jazz as the festivalâs staple music genre, many others, such as blues, soul, funk, or hip hop, pass by. In 1989, legendary jazz pianist Ahmad Jamal brought his trio to the North Sea Jazz Festival. Accompanied by James Cammack on bass and David Bowler on drums, Jamal showcased his excellence.