Halla Arboretum (한라수목원)

Halla Arboretum is the public arboretum of Jeju City, set on the mid-elevation slopes of Hallasan and dedicated to documenting and preserving Jeju Island's distinctive flora — the temperate-to-subtropical mountain plant biodiversity that gives Hallasan its UNESCO World Heritage Natural Site significance. The arboretum spans about 14 hectares with roughly 1,100 plant species across themed botanical zones, including a Jeju-native plant zone, herb-and-medicinal-plant garden, conifer collection, alpine zone, and water garden. Walking trails thread the various zones, with mature trees providing canopy shade through the warmer months. The arboretum also houses a small interpretive museum on Jeju's plant biodiversity and a public greenhouse with year-round tropical-plant displays. Best as a 2–3 hour stop on a wider Jeju City itinerary.