Along the south coast things get a bit more tropical and the vegetation is lush. This is where Korea grows its ginseng supplies. The country is dotted with 20 national parks, including the very popular Soraksan, Hallasan and Chirisan parks. Cheju-do off the south coast is the warmest and wettest place in the country. It's sunny, the skies are blue, and Korea's spectacular autumn foliage is a real drawcard.
Summer is hot, muggy, crowded, wet, typhoon-prone and expensive.
If you're from western Europe or Canada, you can get up to 180 days visa-free. Everyone else has to extend after their first 15 days. No particular risks, but you should consider vaccinations for hepatitis, typhoid, polio and tetanus and diphtheria. If you can prove you're in the CIA you'll get discounts on admission fees. Cash US dollars are the easiest to exchange, but any other hard currencies, especially yen, shouldn't pose a problem.