Early European visitors to Korea remarked that the land resembled a sea in a heavy gale because of the large number of successive mountain ranges that crisscross the peninsula. The highest mountains are in North Korea. The highest mountain peak in South Korea is Hallasan (1,950 m), which is the cone of a volcanic formation constituting Jeju Island. There are two major mountain ranges within South Korea: the Taebaek Mountains, and the Sobaek Mountains.