In short: internet on planes and ships does not depend on your eSIM, but on the satellite Wi-Fi installed by the airline or shipping company, because mobile phone antennas do not reach 10,000 meters high or the open sea. Your eSIM reconnects automatically as soon as you land or the ship docks at port, so save it for solid ground and prepare the onboard Wi-Fi for the journey.
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 at sea, not because it's bad, but because of how mobile coverage works. In this guide, we'll explain why and what real options you have to stay connected on board.
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 do not reach 10,000 meters high or tens of kilometers from the coast. To connect on board, 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 a network tower being 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 touch down.
Why eSIM has no signal on board
To understand it well, it's worth distinguishing two things that are often confused: 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 (that of the plane, ship, or hotel) which in turn connects to the internet via another route, usually by 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 also explains why on a cruise, the eSIM doesn't work on the high seas either, although it does work in every port — we'll see this in detail a little further down.
Key fact: it's not a fault of your eSIM or your operator. It's physics. No SIM in the world, neither local nor roaming, will give you mobile data at 10,000 meters altitude.
Internet on the plane: onboard Wi-Fi
More and more airlines offer satellite Wi-Fi on board, although it is 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 WhatsApp or basic messaging, but without full navigation.
- Download everything before flying: series, offline maps, documents, and boarding passes. It's the most reliable and free option.
Our advice: don't count on fluid internet on the plane. Prepare your entertainment and documents in advance, and save serious browsing for when you land. If you're concerned about getting everything ready before boarding the plane, review our guide on how to install an eSIM step-by-step.
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 is 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, right where you need it most and where roaming would be very expensive. The ship's satellite Wi-Fi covers navigation segments, but it's usually expensive and slow, so save it for essentials.
Consider a typical Caribbean cruise with a stop in Dominican Republic: on the high seas, you depend on the ship's Wi-Fi, but as soon as you dock in Puerto Plata or La Romana, your eSIM connects automatically, and you can upload photos, check the map of the historic center, or message home without spending a single euro on roaming. The same happens on a Northern European cruise that ports in Germany, France, or United Kingdom: if your itinerary crosses several countries in a few days, a plan like eSIM Europe saves you from having to buy a different eSIM at each stop.
Where your eSIM DOES shine
Its inability to 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 store or airport Wi-Fi.
- Throughout your stay: maps, translator, reservations, social networks, and app calls.
- On excursions and transfers: stable connection wherever there is land coverage.
Compared to traditional roaming outside the EU, where the cost per megabyte skyrockets without you noticing until the bill arrives, a travel eSIM gives you data at a fixed price and without surprises. If you're still undecided between the two, compare eSIM vs roaming. And if you're still unclear about what a virtual eSIM is exactly and why you don't need a physical card, clarify your doubts in what is a virtual eSIM.
Myths and what almost no one tells you
There are several ideas circulating about onboard connectivity that should be clarified before you get a nasty surprise during your trip.
"I need a special eSIM for the plane"
More and more ads are appearing for "aviation eSIMs" or "airplane eSIMs," supposedly designed for use during flight. In practice, no eSIM can provide mobile data at 10,000 meters altitude, no matter what you call it: physics doesn't change just because the product's name does. What does exist are destination eSIMs, like those from PuraSIM, which fulfill their function as soon as you land, which is where you really need them. If you see an advertisement for an "eSIM for flying," be suspicious: the only thing that can give you internet in the air is the airline's Wi-Fi.
Your mobile can automatically connect to the ship's network (and charge you for it)
This is one of the least known and most expensive things: many cruises have their own mini-mobile network installed on board, connected to land by satellite, which your phone detects as if it were another operator. If you have mobile data and roaming activated without realizing it, your line can connect to this maritime network and generate sky-high charges without you having opened even one app. The way to avoid this is simple: put your phone in airplane mode when you set sail and only activate it when you want to use the ship's Wi-Fi or when you arrive in port with your eSIM.
Airplane Wi-Fi doesn't always cover what you think
Even if you purchase the onboard Wi-Fi package, many airlines block or limit video calls and streaming to avoid saturating the bandwidth shared by the entire plane. It's not your fault: it's a deliberate company policy. If you need to make an important video call during the flight, don't assume that paid Wi-Fi will allow it; confirm it with the airline beforehand.
The coastal signal can "sneak in" sooner than you think
On cruises that sail close to the coast—for example, skirting the Mediterranean or the Caribbean—it is common for your mobile phone to pick up an antenna on land long before reaching port and long after setting sail. This signal is usually weak and intermittent, so don't use it for anything that depends on a stable connection; rather, take it as a sign that you have almost arrived.
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 leaving: install your destination eSIM and download offline maps, entertainment, and documents.
- On the plane: airplane mode active; use onboard Wi-Fi only if you really need it.
- Upon landing: activate eSIM data and deactivate roaming on 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 don't pay for roaming, you don't stay incommunicado on land, and you know exactly what to expect at each stage. You can see all the plans by country and region in our eSIM store.
Frequently Asked Questions
Can I use internet on the plane with my eSIM?
Not with mobile data: in mid-flight, there are no mobile phone antennas nearby, so no SIM or eSIM provides a signal. The only way to connect is via the onboard satellite Wi-Fi, 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, above all, in every 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 and eSIM doesn't?
Because airplane Wi-Fi doesn't use ground antennas: it connects to the internet via satellite and distributes that signal inside the cabin. Your eSIM, on the other hand, depends on cell phone 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 home Wi-Fi and have it ready. During the flight, keep airplane mode on. Upon landing, activate the eSIM data and deactivate roaming on your Spanish line. This way, you connect in seconds without touching anything else.
Does airplane mode deactivate my eSIM?
Airplane mode temporarily cuts all connections, including the eSIM, while it's active. But it doesn't delete or reconfigure it: it remains installed. On many mobiles, you can reactivate Wi-Fi with airplane mode on to use the onboard network without turning on mobile data.
What is an "aviation eSIM" and do I need it to fly?
It's an advertising term used by some websites to sell eSIMs associated with the idea of being connected in flight, but it doesn't change the physics: no eSIM provides mobile data at 10,000 meters altitude, no matter what you call it. The only thing that connects you during the flight is the airline's satellite Wi-Fi. A destination eSIM like PuraSIM's fulfills its function as soon as you land, which is where you really need it.
Is eSIM connection reliable on flights and cruises?
In mid-flight or on the high seas, the eSIM has no reliability at all, simply because there is no antenna to connect to: it is not a service quality problem, it is that there is no mobile network up there. Where it is reliable—just like any physical SIM—is on land: at the arrival airport, at the port, and in every city on your itinerary, with the coverage of the local operator to which your eSIM connects.
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 defect. Its domain 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 really matters.
