Do I need a visa for South Korea layover?

Nope, it's never been done in the history of the world. :)

You'll need a visa to get out of the international transfer area.

Assuming Incheon, it's probably the best airport in the world, beating both Schiphol and Changi by long shot. It has more amenities than you can shake a stick at, starting with showers. However, three hours will go by fast and nine is a hard stretch. You can scoot into Seoul in an hour and getting back two hours before departure is way more than enough.

If it's Gimpo, it ain't so red hot in comparison.

Which one will depend on the airline used and where you're coming from. Gimpo is even closer to town.

South Korea is a pretty terrific place. I'd buy a visa in a heartbeat for a gratuitous six hours.

If you are traveling with a US passport than you don't need a visa to enter Korea. Korea gives any US citizen a 90 day time frame to visit Korea as long as you are there as a tourist. Korea falls under the visa waiver program. Luckily, all you need is your US passport to enter Korea.

Two answers with conflicting information. Which one is correct? I'm guessing Ed.

Don't guess who is right. Check an official source.
According to the Korean Embassy, you don't need a visa. Check their website
http://usa.mofa.go.kr/english/am/usa/visa/visa/index.jsp

Nope. Jenn' s right.

I looked at a multiple-entry visa in my passport that expired last year and pre-dates the change.

One thing about Ed, he owns up to his mistakes. I bet on the wrong horse.

Thanks to everyone who commented...I appreciate the clarification! :)

btw- I am flying into Incheon, and am pretty excited to see how amazing this airport is in person!

But, but, but . . . . .I don't make mistakes - - I'm just stupid.

There's a lesson here if you hold two passports since one's always out getting a visa or being renewed. I blew off Jenn's response figuring somebody would sort it out later proving my conceited self was correct. I spewed coffee at Laura's response and reached in the drawer and found Passport One which had the old, expired visa which I thought I'd used waltzing through Gimpo right before Christmas but hadn't realized the visa had expired until yesterday - - but there was no entry stamp. Passport 2 had the entry stamp but no visa. The stupidity was: a - - not knowing the rules had changed way back when for a country I visit at least once a year, b - - leaving home with the wrong passport, c - - thinking I was the only one that could possible be right.

The other lesson: Screw up and somebody will eventually get the right scoop out there, which is the purpose of the forums.

Well done, Jenn and Laura.

Amanda:

1. Sorry for the bum scoop.
2. The airport's great but Seoul is magnificent. Get into town as quickly as you can.

Amanda, you will really enjoy yourself. We spent 2 weeks in Seoul last summer and could have stayed another week, easily. If you like cosmetics check out Etude House or Innisfree. They have stores everywhere. Just don't be disappointed when you see a Dunkin Donuts on every corner!