eSIM for Réunion

Réunion is a volcanic island in the Indian Ocean that happens to be a French department, and its network follows the same logic as its roads: a strong ring around the coast, decent links inland where cars can go, and nothing much once you drop into the cirques on foot. If your trip is mostly hiking, that gap is the entire story. Set your line up before you fly and you land in Saint Denis connected, then choose deliberately when to walk out of range.

Getting online when you land

Add the profile to your phone at home while you have wifi, keep it dormant, and enable it once you are on the ground at Roland Garros in Sainte Marie. Most arrivals are long haul from Paris or short hops from Mauritius, and either way the line will attach while you wait for bags.

Nearly everyone rents a car at the airport, so the practical priority is having navigation running before you pull out. Réunion's road network is scenic and unforgiving in equal measure, with the coastal route hugging cliffs and the inland roads to Cilaos and Salazie folding through switchbacks. Knowing which turning you want in advance is better than discovering it at the hairpin.

The networks you'll be on

Data here goes through Orange, which runs 3G, 4G/LTE and 5G. Around the main towns you will find LTE and 5G that feel like anywhere in metropolitan France, and 3G is the fallback in the interior valleys. Speed is not the constraint on this island; line of sight is. A mast on the coast does not help you at the bottom of a canyon, and no amount of bars elsewhere changes that.

Where coverage holds, and where it thins

The coastal ring is solid. Saint Denis, Saint Paul, Saint Gilles les Bains and the lagoon beaches at Hermitage, Saint Leu, Saint Pierre and Saint Benoît are all well covered, as is the fast road connecting them. The tunnels on the coastal route between Saint Denis and La Possession will interrupt you briefly, which is a tunnel problem rather than a coverage one.

Inland it becomes uneven in the way mountains make things uneven. The roads up to Cilaos and to Hell Bourg in Salazie have signal at the villages and lose it repeatedly on the climbs. The Plaine des Cafres and the Plaine des Palmistes along the cross island route are reasonable. The Bébour Bélouve forest and the road toward the Trou de Fer viewpoint drop off quickly.

Mafate is the real one. The third cirque has no road access at all, is reached only on foot or by helicopter, and coverage across it is unreliable to absent depending on which îlet you are standing in. Treat a Mafate trek as offline and plan your gîte bookings, route and water stops accordingly. The volcano is similar: you will typically have something around the Pas de Bellecombe car park and much less once you are down on the lava field walking to the crater. The Piton des Neiges ascent, the Cap Noir ridges and most of the higher trails are the same.

What you'll actually use data for here

Booking beds. The gîtes in the cirques are reserved in advance, often through a central booking service, and the confirmation is what gets you a mattress and a meal at the end of a long day of descent. Sort those while you have signal, then save them.

Trail conditions and volcano status are the second, and they are not optional. Piton de la Fournaise erupts regularly and the access road and trails close when it does; the same authorities post trail closures after heavy rain, which happens often. Checking before you drive up saves a wasted morning. Cyclone season brings its own alerts, worth watching if you are visiting in the southern summer. Beyond that: hiking maps and downloaded route files, tide and swell information if you are swimming inside the lagoon, and everyday navigation between towns whose names all begin with Saint and blur together fast.

Before you fly

Install the eSIM at home, make it your data line, and keep your usual SIM active for bank verification. Confirm the roaming switch is enabled on the travel line rather than assuming a global setting covers it.

Download offline maps of the whole island, since it is small enough that a full download is trivial and interior signal is not. Save your route files, gîte confirmations and car hire details to the device itself. Take a power bank on any multi day trek, because there is nowhere to charge in the cirques and your phone is doing navigation duty. And leave your intended route with someone before you walk into Mafate; that is basic mountain practice here, connected or not.