Dance music lovers in the Netherlands have been raving in the name of research, at a first live gig in over a year.
A total of 1,300 people enjoyed some musical relief at a carefully planned test event in Amsterdam's biggest music hall, the ZiggoDome, which in normal times has a capacity of up to 17,000.
DJ Sunnery James told Reuters he was eager to get back behind the decks.
“At the end of the day you want to play the records in a DJ booth, for people and share the energy. So how I miss it is like I feel like a kid now. I was jumping and screaming like walking in. So yeah, I can't wait to play."
All guests needed to comply with Dutch public health guidelines for 48 hours in advance and had all their movements and contacts tracked through a tag they had to wear.
They were divided into six groups, all with different guidelines on where they were allowed to go in the venue.
Government advisers will use the data on their behavior to inform decisions on how to ease restrictions on mass gatherings in the coming months.
The dance festival is part of a series of test events which also include a business conference, two soccer matches and a comedy show, all with different rules for different groups, to see what works best.