Arriving at Plitvice You will have free time to visit park. The path takes you across Gornja Jezera (Upper Lakes), and then it's time for a magical boat ride within the sound of the waterfalls to Donja Jezera (Lower Lakes). Wherever you are in Pltivice's it's easy to see why its travertine marble formations are such an extraordinary natural phenomenon. The barriers, sills and other forms created in these lakes, karst rivers and streams is still an ongoing process that shapes the wonderful landscapes that make your walk through the park so enjoyable. Its these same travertine formations that have and are still creating the numerous magnificent waterfalls here. Over time, the water changes its course, leaving some barriers dry as it deposits new layers elsewhere. The best way to actually see this happening is when you are standing in front of the Great falls, 78 metres high, The roaring thunder of the water as it hits the ground is unforgettable!