You just landed in Korea.

Activate an eSIM before you reach the ICN/GMP/PUS exit. Free airport Wi-Fi exists but is patchy and many apps (KakaoMap, banking) cooperate poorly with it. Pre-purchase via Klook/KKday — you scan a QR on the plane, you walk out connected.

• Klook eSIM (data-only)
  Cheapest if you only need data. 5/10/30-day packs.
• KKday eSIM (data + small voice)
  When you want a small voice allowance for calls home.
• Airport USIM counter (KT M Mobile/SK)
  Pay at the booth if you want a real Korean number for KakaoTalk / app sign-ups.

Korea runs on Kakao Pay + Naver Pay, but those need a Korean ID. Foreigners use two practical patterns: (a) a regular T-money + tap your Visa for purchases, or (b) WOWPASS — a prepaid card you top up with foreign cash that doubles as transit + payment.

• T-money card
  Cheapest. Any CU/GS25 sells one for roughly ₩3,000–4,000 depending on the design — that card price is not a refundable deposit, though you can claim the leftover balance back later for a small fee. Top up with cash. Works on every bus/subway/taxi.
• WOWPASS
  Top up at airport kiosk with foreign cards in 16 currencies. Combines transit + a real prepaid debit card.
• Cash backup
  Get ₩50,000–100,000 from an ATM at the airport (BC Global / Shinhan / Woori take foreign cards). Many markets are still cash-only.

From ICN you have three real options. From GMP the subway is unbeatable. The wrong choice burns 90 minutes; the right one is door-to-door in an hour.

• AREX Express train
  Fastest to Seoul Station: 43 min, ₩13,000. Buy the ticket at the basement-level AREX counter — foreign cards work.
• Airport limousine bus 6001/6015
  Slowest but cheapest with heavy bags — ~₩17,000 to most major hotels. Pay tap-card or cash at boarding.
• Airport taxi (KakaoT or counter)
  ₩70,000–90,000 to Hongdae/Myeongdong. Worth it after 22:00 or with 3+ travellers. Use the official "International Taxi" lane.

Korean drivers often don't read English. Type your hotel name → get a full-screen Hangul card with romanization and a Kakao map QR the driver can scan. Foreigners who do this once never go back.

Korean menus skip allergens. Use the translator before you order — set your allergies + spice tolerance once, then photograph any menu. SeoulTrip flags dishes that don't fit your profile.