Sangunbulil (산굼부리) is a unique crater on Jeju Island that does not have a volcanic lava body. It is about 100 meters high, with a circumference of about 2 kilometers and a total area of 298,000 square meters. It is a treasure trove of natural plants with more than 420 species of temperate, subtropical and alpine plants. Sangunbulil is a crater with a circumference of more than 2 kilometers and is a natural protection object. It is located on the flat land southeast of Jeju City, with a diameter of 650 meters, a depth of 100 meters and a circumference of 2,070 meters. From the air, Sangunbulil looks like an artificial circular stadium. There are many kinds of plants here. Temperate trees (red thorn tree, red nanmu) and precious plants such as winter strawberry grow on the north side. The south side of the crater is a typical temperate forest (west wood, maple, four-orange flower, etc.). Various trees of different natures grow in the limited space of the crater, which is highly valued in academia. There are many sights to see on the mountain, including entrances made of stones, rock pools, craters, etc.