Lotte World is an amusement park in the middle of Seoul and is the world’s largest indoor theme park which is open all year around. There is also an outdoor amusement park called “Magic Island”, an artificial island a lake linked by monorail, shopping malls and other stuff for a whole day trip.
The Lotte World is located at the Jamsil Station, on the Line 2 and Line. The Entrance is around 40,000 to 23,000 Won. As Student you can get a discount with your Korean Student card and your Woori Bank card, what you make when you arrive in Korea with your buddy. At the first the park looks really childish and you see everywhere mascots and fluffy stuff, but on the magic island you can find some good rides, that are more suited for older people. Go there early or late in the afternoon, because the park is always full and the lines for the attraction can be one hour long. At night the park is a good picture spot, there is a castle which is illuminated in different colors and there is an ice skating rink in the middle of the building.
A good advice don’t go with people who are higher than 1.90, because the rides a constructed for Koreans.