Among Poland's biggest, craziest and most popular music festivals, Open'er is best experienced by reserving a campsite and coming prepared for four days of partying in the sun (and the rain) as some of the world's biggest touring acts perform on several stages at the Gdynia-Kosakowo Airfield. Bruno Mars, Gorillaz, Depeche Mode, Massive Attack, Fleet Foxes, David Byrne, MØ, Kaleo, and Sevdaliza are all set to perform across 3 stages. Single-day and weekend tickets are also available, and the earlier you buy, the more you save.