Nationals of most Western countries, including the United States, Canada, and European Union members, are automatically granted visas on arrival to Korea that entitle them to stays between 30 days and six months. Try to ensure you’re traveling on a passport with over six months’ validity—this isn’t a strict requirement for entry into Korea yet, but passports that expire sooner can raise eyebrows among airline staff and immigration officials.
The vast majority of visitors to Seoul [1] arrive via Incheon International Airport, which is built on reclaimed land off South Korea’s west coast, around 52 kilometers (32 miles) west of Seoul proper. Fleets of comfortable “limousine” buses are available to ferry arrivals to various points throughout the city and its suburbs, and a new airport rail line also connects the airport with Seoul’s central train station and the rest of the extensive subway network.
Taxis are also an option, though at 60,000-80,000 won on average for the trip downtown are fairly pricey. The journey into the city takes around 45 minutes to an hour under normal traffic conditions.
Once you’re in Seoul, although rental vehicles are available don’t even think about driving yourself around—the aggressive local driving style, the city’s tangled layout, and a lack of English signage and parking are likely to make it a traumatic experience.
Instead rely on the excellent public transportation system, particularly the subway, which is cheap, easy to navigate, covers nearly all corners of the city, and rarely suffers from delays or breakdowns. This can be supplemented as necessary with taxis, which are readily available and very affordable for shorter trips.
Links:
[1] http://www.moon.com/destinations/seoul/discover-seoul