13 hrs in Seoul Korea, what do i do

Ok so i will be flying into the Incheon International Airport at 5am in the morning and i dont have to leave until 7pm at night.

What suggestions do you have for me to do in that amount of time, whats the best things to see?

Is it easy to leave the airport and make it back in time for my flight.

what else should i know?

Thanks for any help you can give.

It's about 60-90 minutes from the airport to downtown Seoul by limousine bus. Thye run every ten minutes or so to all over the city. If you get one going to Jongno then you'll be within easy subway access of all the major tourist stuff (Gyeongbok Palace, Insadong, Namsan Tower, Namdaemun Market etc) Be sure to leave enough time to get back though, because the traffic out of Seoul may well be worse in the late afternoon.