Medvednica is a mountain in central Croatia, just north of Zagreb, and marking the southern border of the historic region of Zagorje. The highest peak, at 1,035 m is Sljeme. Most of the area of Medvednica is a nature park , a type of preservation lesser than a national park. The area of the park is 228.26 km and about 63% is covered with forest. During Miocene and Pliocene, the mountain was an island within the Pannonian Sea.