South Korea treats mobile internet as serious infrastructure. The country regularly tops global rankings for average connection speed. In Seoul, you'll have 5G in the subway, underground shopping malls, and pretty much everywhere above ground. It's genuinely impressive.
Networks and coverage
Three main carriers: SK Telecom, KT (Korea Telecom), and LG U+. All three have excellent nationwide coverage. SK Telecom has the best rural reach and is typically the network used by international eSIM providers. Even in mountainous areas like Seoraksan National Park, coverage is better than you'd expect.
Seoul subway signal is a particular highlight - continuous LTE/5G across almost all lines, including underground sections. No more losing Maps in the middle of a complex transfer.
What you need for a Korea trip
Korea uses a lot of apps you'll want data for. Kakao Maps is actually better than Google Maps for Seoul - more accurate public transit info, better walking directions in the dense city streets. T-money app for transit card management. Naver for local restaurant recommendations (better than Google for Korean-language venues).
Papago for translation - better than Google Translate for Korean specifically, especially for nuanced text. All of these are light on data, but you'll use them constantly.
How much data for South Korea?
Korea is a city trip for most people - Seoul, maybe Busan, Jeju Island. It's compact and heavily served by excellent public transit. I used 3.2GB on a 10-day trip that included heavy Maps use, video calling, and some streaming on the KTX train between Seoul and Busan.
A 5GB plan for a week is comfortable. For two weeks or if you're doing a lot of video content, go 10GB. The 3GB plan is probably fine for a short city break if you're disciplined.
Jeju Island
Good coverage across Jeju, including the west coast and the Hallasan mountain area. You can navigate hiking trails with signal - the trailhead areas specifically have decent coverage. The east coast (Seongsan Ilchulbong, Manjanggul cave) is well-covered.
Buying vs airport SIM
Airport SIM vending machines at Incheon are well-known and popular. They're convenient and reasonably priced. An eSIM is slightly cheaper and means you're connected the moment you land, rather than after you navigate to the vending machine, work out the instructions (in Korean), and wait for activation.
Check /esim-in-south-korea for current plan pricing and options.
Traveling to South Korea?
Browse affordable eSIM data plans for South Korea. Plans start from $1.40. Instant activation, no roaming fees.