Using an eSIM in Jeju

What Jeju is like on a phone

Jeju is where Koreans themselves fly for a break, as much as foreign visitors do. Most people rent a car, because the sights are spread around the rim and the buses are slow. In the middle stands a single large volcano that pulls cloud in and rewrites the weather within an hour. The ring road along the coast is well served; climb towards the centre, or drop down the black basalt cliffs to the water, and the connection starts following the terrain rather than the distance.

When you land

Everyone lands at Jeju International (CJU), right beside Jeju City on the north shore. Turn the eSIM on in the cabin, because the next step is finding the rental desk — usually a shuttle ride outside the terminal — and showing the booking on screen. Without a car you take the ring-road bus, which always takes longer than the map estimates. Driving out along the coast the line is continuous through the built-up north, then changes character as the houses thin out.

Where coverage changes

The coastal ring and the two main towns are reliable, and the small shore villages usually are too, because they sit on that road. The clear change is the climb into the interior, where the line thins inside the high forest and can disappear altogether on sections of the trail. Beaches tucked under cliffs and the lava tube caves are two other places not to expect a connection at all. On the boat to the small offshore island the signal dims mid-water and returns as the pier comes up.

What a day here costs in data

A day driving the ring road costs about 1–1.5GB, since navigation runs continuously and you keep searching for the next stop while moving. Walking a coastal trail all day uses less if you downloaded the route first, but it eats battery, because the screen wakes constantly and winter sea wind chills the handset. Filming sunrise from the crater rim and sending it straight away means allowing extra for a large file at the worst time of day for a battery.

Districts travellers ask about

• Jeju City — The northern side, with the night market and the densest run of restaurants; smooth across the whole district and the right place to lock in accommodation and activities before driving on.
• Seogwipo — The southern town, where waterfalls drop towards the sea beside a working harbour; the streets are good, though the paths down between rock walls to the falls go quiet while you are at the bottom.
• Aewol — A western shoreline lined with cafés built onto the black rock; the coast road is well served, but parking is tight on weekend afternoons, so look at traffic before you set off.
• Seongsan — The seaside crater on the east coast that people climb for sunrise; the stairway is steep with weaker patches on the way up, so buy or save the entry ticket before you start climbing in the dark.

Day trips out of the city

• Udo Island — A short crossing from the east coast, with the usual mid-water dip; the island's ring road is fine, but check the last sailing before you board, because the timetable is adjusted for wind and swell.
• The Hallasan trails — The climb into the island's centre has long unserved stretches and weather that turns fast. Follow the park's own registration rules, take the cut-off times from the official notice because they change with the season, and tell someone when you expect to be down.
• The small southern islets — Boats leave the southern harbours for islets with barely any houses on them; coverage there is patchy and thinner than on the main island, so download the walking map and write down the return sailing before you leave the pier.