Glass Castle

A large piece of volcanic rock said to be the solidified remains of Yimugi, a water dragon. Whilst the legends behind just how he got himself turned to stone in that position vary, it hasn't diminshed his influence, as the surrounding suburb is called Yongdam by extension: literally "Dragon's Head Rock". Just about 100 m to the east you can find the lesser known, but probably prettier Yongyeon Pond, a picturesque canyon straddling a pleasantly turquoise pond with a pavilion perched overhead. Again, a dragon features heavily in the legendary history of this site, but simply that it visited. A festival is held here in May. If all this talk of dragons is making you want to sit on a horse for some reason, then there is an old guy out the front who aggressively and inexplicably offers this service for a fee. Both sites are lit up spectacularly at night.

It is close to Jeju Airport, and it is enough distance to ride a bicycle. There are white and red pony lighthouses, the slope of the beach is gentle, and there is a pine forest nearby, so it is a good place to enjoy the scenery and take a walk.

A special defense unit of the Goryeo kingdom rebelled against the invading Mongolian army in 1270, and eventually retreated to Jeju Island for a last stand. They held off the Mongolian forces here for 2 years before they were all killed at a fortress built here.

A beautiful forest of old-growth nutmeg trees, accessed by flat, gravel walking paths. In the center of the forest stands a Japanese Torreya tree that is more than 800 years old, the oldest tree on Jeju. There are two connected walking paths: a short trail takes about 30 minutes and the longer loop perhaps double that.

Museum dedicated to the Haenyeo (female divers). Small but interesting. Nice views from the top.

Manjanggul Cave is a famous lava tube and a UNESCO-listed world natural heritage site. There are numerous lava caves all over the world, but it is said that it is difficult to find a place like Manjanggul Cave that has well-preserved shape and topography even though it is hundreds of thousands of years old. The interior, which looks like an underground palace, has a magnificent and profound atmosphere, especially stone turtles like elaborate sculptures, which are popular with tourists because they look like Jeju Island. As such, the inside of the cave is accompanied by lava stalactites on the ceiling and lava wings on the wall, creating the mystery of the underground world. The 7.6-meter-high lava stone pillar at the end of the open section is the largest in the world. The closed section is not visible to tourists, but it is known that bats, landfills, crayfish worms, farm-footed spiders, and little oyster spiders live there. Manjanggul Cave is protected as a natural monument along with nearby Gimnyeong Cave.