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 (3,396 ft) is Sljeme. Most of the area of Medvednica is a nature park (park prirode), a type of preservation lesser than a national park. The area of the park is 228.26 km2 (88.1 sq mi) and about 63% is covered with forest. During Miocene and Pliocene the mountain was an island within the Pannonian Sea.