eSIM for Czechia: Prague plus day trips to Karlovy Vary and Krumlov
A classic Czechia trip is a few days in Prague plus one or two day trips out of town: to the mineral springs of Karlovy Vary, or to the medieval town of Český Krumlov. All three places differ in scale and pace, and each needs data for a different reason — from navigating Prague's confusing old lanes to checking a bus timetable that doesn't run every hour. Here is what helps at each stage of the trip, from landing in Prague to the ride back from the spa town.
Walking Prague: why navigation apps get confused in the Old Town
Historic Prague — the Old Town, Malá Strana, the area around Charles Bridge — is built up with narrow, winding streets that look logical on a paper map but are confusing in person even with navigation in hand. Here mobile data isn't about speed, it's about not losing an hour looking for the right turn.
4G in central Prague is stable, including districts like Vyšehrad and Žižkov beyond the tourist core, so loading a map or saving a restaurant's pin rarely causes any trouble. Even in the tight inner courtyards of Malá Strana, where buildings stand almost shoulder to shoulder, signal usually holds up well enough for a page to load.
Getting around Prague: trams, the metro and the PID Lítačka app
Prague's public transport — trams, a three-line metro and buses — runs on a single PID system, and the easiest way to buy a ticket is the PID Lítačka app, rather than working out an unfamiliar ticket machine at the stop.
The same tram ride can take five minutes on a direct line or half an hour on a diversion if a section is closed for repairs, so it's worth checking the app before boarding instead of relying on memory from a previous trip.
- PID Lítačka — tickets and timetables for trams, the metro and buses
- an offline map of the Old Town and Prague Castle for narrow courtyards with weak signal
- a translator for pub menus, which aren't always available in English
- a map of ATMs and exchange offices — cash koruna comes in handy at small cafes
Czechia is in the EU but pays in koruna, not euros — open your banking app and check the exchange rate in advance, even at the airport.
Karlovy Vary in a day: the bus from Prague and colonnades with no Wi-Fi
Regular buses run to Karlovy Vary from Prague, taking about two hours, and it's easier to check the timetable in the carrier's app than to hunt for a paper one at the bus station. Along the way and in the town itself, 4G holds up evenly — this is a well-known spa town with a constant flow of visitors, not remote countryside.
The drinking colonnades along the Teplá riverbank, where you sample the mineral springs, usually have no Wi-Fi, and mobile data comes in handy for checking which spring is which and its temperature, or finding an open wafer stand nearby. The spa quarter is compact, and most of the town is easy to cover on foot in a single visit.
Český Krumlov: a small town where signal isn't the issue, the bus schedule is
Český Krumlov is small, and coverage there is solid almost everywhere, including the castle complex above the Vltava river. The real challenge isn't finding signal, it's not missing your bus or train back: outside peak season, services run less often than a visitor used to city timetables might expect.
It's easier to check the current timetable in the carrier's app right there than to trust a printout from your hotel that's a week old — routes do change from time to time. For the same reason, check the schedule both the evening before and the morning of your departure: the last bus to Prague can leave earlier than it does in high season.
A city weekend or a week with day trips: sizing the package
For a few days in Prague itself — museums, cafes, evening walks across the bridges — 3–5 GB is usually enough, since most of the load is maps and messengers rather than streaming video. Even a packed weekend of photos from Charles Bridge and the view from Petřín Tower rarely goes beyond that.
If Karlovy Vary and Krumlov are on the itinerary, add some extra for the road: time on the bus or train often goes to video or music rather than conversation, so a week's trip with two day trips fits more comfortably into 6–8 GB. You can always buy an extra package mid-trip if you run low early.