In the south western portion of Sweden sits the large Gothenburg Municipality, location of the city of the same name. Off the coast, speckling the waters of the Kattegat, are the tiny islands known as the Archipelago of Gothenburg. One of the islands in the Southern Archipelago, Brännö, holds a festive dance party at one of its ports every Saturday evening during the summer months. Typical performers are local musicians, but this past weekend, the tiny crowd at that tiny stage on that tiny island got a surprise treat when Bon Iver’s Justin Vernon and The National’s Aaron Dessner delivered an impromptu jam (via Gaffa).

Both bands are in the region ahead of their appearances at the HAVEN Festival in Copenhagen, Denmark later this week. Despite being on their day off, however, it seems the musicians just can’t ignore the call of the stage — even if there are only a dozen people standing in front of it. Check out Vernon and Dessner’s intimate, improvisational groove up above.