On Day 13 of our tour we visited the Plitvice Lakes National Park located in the mountainous karst region of central Croatia, not far from the border of Bosnia-Herzegovina. This is one of the largest and oldest national parks in the country, and was designated a UNESCO World Heritage Site in 1979 due to its tufa lakes, cascades and cave systems. The park has 16 lakes created by a series of both small surface rivers and subterranean karst rivers, and are interconnected via the same water flow. The lakes are separated by natural dams made from limestone deposits that have formed as a result of a continuous interaction between moss, algae and bacteria. There are two separate clusters, the upper and lower lakes. We drove from Zagreb for more than two hours through the mountainous Karlovac County to reach the area. Once there, we explored the lower lakes portion of the park.