It's a common question: if you're traveling with an eSIM, will you be able to connect to the internet in mid-flight or in the middle of the sea during a cruise? The short answer is that an eSIM alone won't work in the air or on the high seas, and not because it's faulty, but because of how mobile coverage works. In this guide, we explain why and what real options you have to stay connected onboard.
Does eSIM work on a plane or ship?
No, an eSIM does not work on its own in mid-flight or on the high seas. An eSIM connects to mobile phone antennas located on land, and those antennas don't reach 10,000 meters in altitude or tens of kilometers from the coast. To connect onboard, you need the plane or ship's Wi-Fi, not mobile data.
It's a logical misunderstanding: since the eSIM gives you internet in any country as soon as you land, it seems like it should also work during the journey. But the technology is the same as your usual mobile phone: it depends on there being a network tower nearby. In the air and in the middle of the ocean, there simply isn't one. That's why airplane mode cuts off all mobile connections during the flight. The good news is that your eSIM remains perfectly installed and ready to connect as soon as you set foot on solid ground.
Why eSIM doesn't get signal onboard
To understand this well, it's helpful to distinguish between two often-confused things: mobile data and Wi-Fi.
- Mobile data (what your eSIM provides): requires a land-based operator antenna within a reasonable radius. Typical range of a few kilometers. Useless at cruising altitude or on the high seas.
- Wi-Fi: is a local network (from the plane, ship, or hotel) which in turn connects to the internet via another route, usually satellite when you are far from land.
In other words: in the air and at sea, the only gateway to the internet is satellite, and you can only access satellites through the Wi-Fi installed by the airline or shipping company. Your eSIM, like any SIM, does not communicate directly with satellites. This is the same reason why on a cruise, the eSIM also doesn't work on the high seas, although it does work in every port.
Key fact: it's not a fault with your eSIM or your operator. It's physics. No SIM in the world, local or roaming, will give you mobile data at 10,000 meters altitude.
Internet on the plane: in-flight Wi-Fi
More and more airlines are offering in-flight Wi-Fi via satellite, although it's not universal or always free. These are your real options during the flight:
- Airline Wi-Fi: you connect to the company's portal and pay for a package (per segment or per hour). The speed is just enough for messaging and email, not for video.
- Included messaging: some companies offer free basic WhatsApp or messaging, but without full browsing.
- Download everything before flying: series, offline maps, documents, and boarding passes. This is the most reliable and free option.
Our advice: don't count on fluid internet on the plane. Prepare entertainment and documents in advance, and save serious browsing for when you land. If you're concerned about properly activating your connection upon arrival, review when to activate your eSIM, before or after traveling.
Internet on a cruise or ship
The same thing happens on a cruise, with an important nuance: the signal changes depending on where you are. The rule is simple:
| Situation | Does eSIM work? | What to use |
|---|---|---|
| On the high seas | No | Ship's satellite Wi-Fi (paid) |
| Near the coast | Sometimes, with weak signal | eSIM data if there's coverage |
| In port / excursion | Yes | Country's eSIM data |
That's why an eSIM is still very useful on a cruise: even if it doesn't work on the high seas, it does connect you in every port and excursion, exactly where you need it most and where roaming would be very expensive. The ship's satellite Wi-Fi covers navigation stretches, but it's usually expensive and slow. You can find more details in the eSIM for cruise guide.
Where your eSIM DOES shine
The fact that it doesn't work in the air doesn't detract from its value: the eSIM is designed for 99% of your trip, which happens on land. That's where it saves you expensive roaming and the paperwork of local SIMs:
- As soon as you land: internet in seconds without looking for a shop or airport Wi-Fi.
- Throughout your stay: maps, translator, reservations, networks, and app calls.
- On excursions and transfers: stable connection wherever there is terrestrial coverage.
Compared to traditional roaming costing €10-€20 per day outside the EU, a travel eSIM gives you data for a fraction of the price and no bill shocks. If you're still weighing your options, compare them in eSIM vs. roaming. And to choose based on your destination, take a look at how to buy an eSIM online.
Realistic plan to stay connected on your trip
Putting it all together, this is the plan that truly works for a trip with flights or sea voyages:
- Before you leave: Install your destination eSIM and download offline maps, entertainment, and documents.
- On the plane: Active airplane mode; only use in-flight Wi-Fi if absolutely necessary.
- Upon landing: Activate eSIM data and deactivate roaming for your Spanish SIM.
- On the ship: eSIM in ports and for excursions; satellite Wi-Fi only for essentials on the high seas.
With this scheme, you won't pay for roaming, you won't be incommunicado on land, and you'll know exactly what to expect at each stage. You can see all plans by country and region in our eSIM store.
Frequently asked questions
Can I use the internet on the plane with my eSIM?
Not with mobile data: in mid-flight, there are no cell phone antennas nearby, so no SIM or eSIM will have signal. The only way to connect is with in-flight Wi-Fi via satellite, which many airlines offer for a fee. Your eSIM will work again as soon as you land.
Does eSIM work on a cruise?
Not on the high seas, because there is no terrestrial mobile coverage; there you only have the ship's satellite Wi-Fi. But near the coast and, especially, in each port and excursion, the eSIM does work and saves you expensive roaming. That's why it's still worth it on a cruise.
Why does airplane Wi-Fi work, but eSIM doesn't?
Because airplane Wi-Fi doesn't use ground antennas: it connects to the internet via satellite and distributes that signal within the cabin. Your eSIM, on the other hand, relies on cell towers on the ground, which don't reach cruising altitude. They are two different technologies.
Do I need to do anything with the eSIM before flying?
Ideally, install it before your trip with Wi-Fi at home and have it ready. During the flight, keep airplane mode on. Upon landing, activate the eSIM's data and deactivate roaming for your Spanish line. This way, you'll connect in seconds without doing anything else.
Does airplane mode deactivate my eSIM?
Airplane mode temporarily cuts all connections, including the eSIM, while it's activated. But it doesn't delete or reconfigure it: it remains installed. On many phones, you can reactivate Wi-Fi with airplane mode on to use the onboard network without turning on mobile data.
Conclusion
An eSIM won't give you internet at 10,000 meters or in the middle of the ocean, and that's normal: it's physics, not a flaw. Its terrain is solid ground, where it saves you roaming and connects you in a minute. Prepare offline entertainment for the journey and let the eSIM do its job upon arrival: choose your eSIM plan for the destination and travel connected where it truly matters.
