The KTX high-speed train is the best option: about 2.5–3 hours from Seoul Station to Busan Station, right in the city.
- KTX, or SRT (from Suseo Station near Gangnam): book on the Korail app or Korail's English website.
- Express bus: cheaper but takes about 4–5 hours.
- Domestic flight Gimpo – Gimhae: quick in the air, but no faster than the KTX once you add airport time.
Note: on weekends and around Chuseok and Seollal holidays KTX tickets sell out fast, so book a few weeks ahead.