Although there's no direct train from Seoul's Incheon International Airport, buses make the 90-minute trip downtown. Use a bus pass instead of cash and you'll get discounts over single fares and for buses that visit most popular tourist spots [source: Seoul Stop Over Buses].
In 2004, Seoul revamped its public bus system to make it less confusing. Now the city uses four different types of public buses in a simplified route system [source: Korea Tourism Organization]. The Seoul Metropolitan Subway, however, is one of the largest in the world, and is an easy way to navigate the city.
Purchase a T-money card at subway stations, kiosks and convenience stores to save money over single fares on buses and subways. The Seoul City Pass is another good option, offering users the flexibility of taking up to 20 bus or subway rides in a 24 hour period. If visiting areas outside of Seoul, such as Busan and Gwangju, consider the high-speed bullet train, Korea Train Express.