Over the next four days, more than 120 musicians from all over the world will perform, including British singer Anna Calvi, who opened the festival, followed by the electro duo The Ting Tings.
The first day also includes performances by Thievery Corporation, Groove Armada, Friendly Fires, The Notwist and Future Islands.
Many young people from Croatia and abroad started arriving at the festival camp on Monday. This year's festival is expected to draw more than 40,000 people from all over Europe.
The organiser has paid a lot of attention to the festival's green aspect, including ecology workshops and the presentation of a solar car and a solar bicycle.
Performers also include Stephen Malkmus & the Jicks, The Jon Spencer Blues Explosion, The Horrors, Wild Beasts, The Roots, The Vaccines, The xx, and Swans.