This water park is best for kids. There are a lot of activities for kids here including the lazy river, tide pool, the water playground, and various water slides. If I was still a kid, I would have had a blast coming here in the middle of winter.
But for adults, the waterpark is a little lackluster and your options are limited. There is only one water slide that adults can go on, and adults are only allowed to use the double tube. The tubes provided in the lazy river are too small for adults. The pool with the massage jet streams was the highlight of this park. There were about 4 different jet stream massage options, which was fun and relaxing.
You will also be asked to pay for a lifejacket and swimming cap to go in the tide pool, lazy river, and the pool with the massage jet streams (cap only). A lot of people wore their baseball caps instead of swimming caps and the lifeguards didn't seem to mind.
I came here with my family on January, and we were able to get discounted tickets to the waterpark. It was around 28,000 won per adult, but the regular admission fee is 55,000 won. Another thing to note is that if you can't read Hangeul or understand any Korean, you will have difficulty getting around the park. Very few signs are written in English, and some of the staff don't really know English. After you pay, you have to take your shoes off, put them in a shoe locker, and then go to a locker room to change before getting into the waterpark. I did not see an entrance to the waterpark without going through the gender-separated locker rooms.