For anyone who is still not sure whether to visit Jeju island or not.. I found a site that suggests things to do in the island:
1. Hike up Hallasan (to the top via Seongpanak or the Gwaneumsa route, or just up to the Witsae Oreum via Eorimok, Yeongshil, or Donneko routes)
2. Take a ferry to Marado from the Moseul harbour and be as far south as you can get in South Korea.
3. Go snorkling or scuba diving. An English-speaking scuba centre has a website, here.:
http://www.bigblue33.co.kr/english/fr_introduction.htm4. Walk the Jeju Olle trails and get a good view of the Jeju natural and urban landscapes.
5. Visit Loveland and take naughty pictures of yourself and statues.
6. Stay at a minbak on the east coast in Seongsan, and catch a sunrise / climb Seongsan Ilchulbong.
7. Like raw seafood? Any town close to the water will have its share of restaurants offering local fare.
8. Take the ferry from Seongsan harbour and visit Udo Island for a day or two. There's a nice white sand beach there, you'll probably see a Haenyo, and did you know they grow some pretty tasty peanuts on Udo?
9. Visit the Haenyo museum in Hado-ri.
10. Rent a car and drive down some of the little cement farmer roads. You'll never know what you might come across.
11. Go hiking on any of the many oreum on Jeju.
12. Want to see a lava tube? Visit the Geomunoreum lava tube system, Manganggul. Afterwards, visit the Gimnyeong Maze park just down the road to see how fast you can make it through the hedge maze.
Or for another lava tube, visit Micheongul and then make yourself a clay bowl after.
13. Visit Sanbangsan. It is an impressive mini-mountian right by the southwestern coast. Technically you're now allowed to climb it anymore, but on the south side is a nice temple with a Buddha in a cave.
14. Close by Sanbangsan is Hamel's Ship, a museum about the Dutch crew who shipwrecked on Jeju in the 1600s.
15. Visit a random attraction. There's a bunch: the Teddy Bear Museum (cute?), the Dak Paper Doll Museum (creepy?), Chocolate Museum, Africa Museum, Trick Museum, Mini Mini Land, Dinosaur Land, Crocodile land, Elephant Land... The list goes on. Some of these attractions are nothing to write home about, but some are worth a look. Actually, please don't visit any attraction that uses live exotic animals, as the animals are kept in pitiable conditions and the places aren't worth supporting.
16. Take a trip to the Jeju Folk Village in Pyoseon and check out Jeju culture. They have performances at certain hours, as well.
17. Or visit Seongeup, a village of traditional Jeju houses where people still live.
18. Jeju Horses! A living reminder of the past Mongolian occupation, you can see them in their pastures or bet on a race at the Jeju Race Track. Or visit the Mongolian Circus to see them in action.
19. Looking for a place to stay? Unless you need to stay in a posh hotel, look for a 민박 or pension or homestay by a place you'd like to see more of.
20. Vegetarian? There are some nice but simple restaurants on the island.
21. Do a temple stay at Yakcheonsa (약천사), which is said to host the largest prayer hall in Asia. English shouldn't be a problem.
22. If you time it right, you can catch a Jeju United soccer match at the the 2002 World Cup Stadium down in ShinSeogwipo.
23. Ha, it's raining? Well, that can be some of the best times to see Jeju's waterfalls. Some of them only exist after a rain since we have no continuous rivers on the island.
24. Jeju oranges. The orange harvest season starts in November/December, and you can pick up oranges then for cheap at the market. The Hallabong season doesn't start until about January/February, but once it does, you can buy some of the tastiest oranges on Jeju for cheaper than on the mainland.
Oranges are available for tourists year-round, but winter is the best time to get them fresh.
25. Visit a 5-day market and buy some veggies from the halmangs. In Jeju-si, they occur on days ending on a 2 or a 7 and in Seogwipo it's 4 and 9. There are other 5-day markets as well, but Jeju-si and Seogiwpo-si are the biggest.
26. Want to surf? You might be able to catch a wave down in Jungmun. There is a hotel that rents surfboards down there, but you may want to check with tourist info about that.
27. Get a Jeju map at any Jeju Tourist Centre. See if there is anything on there that strikes your fancy, and enjoy the adventure of getting there.
28. Bring a tent and camp out at one of the many beaches on the island.
29. Go fishing! Rent equipment and fish on shore, or hire a boat and captain to take you out on the water (better if you have a group of people, cost-wise).
30. Like to golf, and have some money to burn? Go golfing at one of Jeju's many golf courses (that is, if they will let you in)
31. Paragliding lessons on some of the Jeju oreum. Best to ask about this at a Tourist Centre, or by calling 064-1330 on Jeju
32. Learn a little of the Jeju dialect and impress the locals. Bound to make you friends, especially among the older generation.
If you're interested, there's a new high speed ferry travelling between parts of Jeollanam-do and Jeju. Travelling time is shorten from 5 hours to 1hr 45min! Read more in the above site and