Hallasan (한라산 / 漢拏山) is the highest mountain in South Korea, standing at 1,950 meters (6,400 ft). The park is in the center of Jeju Island and the peak can be seen from almost all places on Jeju itself. It is a UNESCO World Natural Heritage Site.
The park is based around mountain of Hallasan which is an extinct volcano, and only has one dominating peak. The top of the mountain has a crater lake known as Baekrokdam.
Most routes are accessible via bus — simply state your chosen path at the ticket booth in the inter-city bus terminal — although in winter the final buses back can leave quite early (around 5). Trails sometimes put up “closed” signs around midday in winter to prevent people getting stuck. Also note that the inter-city buses will drop you at the carpark. The often 1-2 km sealed road walk up to the trail start is not included on trail length approximations on local signage and documentation so bear this in mind.