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. Last year's line-up included Bruno Mars, Gorillaz, Depeche Mode, Massive Attack, Fleet Foxes, David Byrne and more performing across 3 stages. For 2019, the dates are set, but no artists have been announced. Single-day and weekend tickets are available, and the earlier you buy, the more you save.