Haranggaol is a tourist town located on the northern shores of Lake Toba. The city is a part of the Simalungun regency. Haranggaol features a cave by the shores of Lake Toba named Goa Haranggaol. The cave belongs to the sub-district Liang Atas in the Purba Pasir district. According to the local tradition, this Haranggaol cave was once used by the kings of the Batak to enjoy the beauty of Lake Toba.