KTX trains and the express buses, and the jjimjilbang night

The KTX high-speed train links Seoul with Busan in about two and a half hours; book on the Korail app or site, where foreign cards work. Express buses from the Seoul terminals reach everywhere else cheaply and comfortably. For a cheap, memorable night, a jjimjilbang (Korean bathhouse) lets you sleep on the heated floor of the common room for the entry fee; Siloam near Seoul Station and Spa Land in Busan are famous. Museums in Seoul are largely free, including the National Museum of Korea.