South Korea has some of the fastest mobile internet in the world, but there's a quirk few travelers know about in advance: Google Maps works in a limited way there. Here's which eSIM to get for Seoul and Busan, and what to use for navigation instead.
For a week in Seoul with navigation, a translation app and heavy social media use, 5–8 GB is usually enough. For a multi-city trip — Seoul, Busan, Incheon, Jeju Island — with maps and on-the-spot bookings, get 10 GB or more.
Under South Korean law, detailed mapping data can't be exported abroad, so walking and driving navigation in Google Maps is limited there. Most travelers use local apps like Naver Map or KakaoMap instead — both are available in English and give more accurate directions.
Coverage is fast and reliable almost everywhere in Seoul and Busan, including the subway. Jeju Island also has good coverage in tourist areas and along the main roads.