Will the internet work on the ferry from Phuket to Phi Phi?

It will work as you leave the harbours and approach the islands. In the middle of the crossing, out on the open sea, it's normal to have no signal for a long stretch. That's why it's best to download your maps and tickets in advance.

Which network is better for the Thai islands?

On the southern islands, AIS usually has the widest coverage. TrueMove H and dtac work very well in the cities, but on the smaller islands AIS is considered the more reliable choice. A good travel eSIM automatically connects to the strongest available network.

Why does the internet weaken during the Full Moon Party?

The problem isn't coverage. Because tens of thousands of people use the same cell towers at once, the network becomes overloaded. That's why internet speed drops and messages can be delayed.

How many GB of data do you need for a week-long island trip?

For maps, messaging and photos, 3–5 GB is usually enough for a 7–10 day trip. If you video-call or watch video every day, a 10 GB or larger plan makes more sense.

If I use an eSIM, will I keep my own phone number?

Yes. A travel eSIM works alongside your physical SIM card. Your own number stays active, your WhatsApp account doesn't change, and you receive your bank OTP codes just as before.

When should I set up the eSIM?

The best time is before your flight, at home on Wi-Fi. Once you arrive in Thailand, switch your data connection over to the eSIM and start using the internet within a few minutes.

Where a Thailand eSIM really works: Phuket, the islands and the boats in between

LSThe LimitSim team

Mainland Thailand and its larger islands are almost trouble-free when it comes to internet. Maps, video calls and social media all run smoothly in Bangkok, Phuket Town, Ao Nang and Chaweng. The real difference starts the moment you leave the shore. Longtail boats, island-hopping ferries, dive sites and jungle routes are exactly where the signal weakens or drops out completely. This guide explains where coverage is strong and where it is weak across Thailand's most popular islands, and what to sort out in advance so you get the most out of a travel eSIM.

Which networks does an eSIM use in Thailand?

Thailand has three main mobile carriers: AIS, TrueMove H and dtac.

In Bangkok, Chiang Mai and the other big cities their performance is very close to identical. On the southern islands, though, the difference becomes noticeable. On Phuket, Phi Phi, Samui, Koh Tao and the other tourist islands, AIS usually has the widest coverage and holds a signal longer at remote spots.

A travel eSIM doesn't create its own mobile network. It connects to one or more of these carriers. That's why an eSIM's coverage is only as good as the coverage of the local network it's using. No eSIM — ours included — can conjure up internet where there is no signal, or speed up an overloaded cell tower.

The best eSIM plans connect your phone automatically to the strongest available network and shield you from international roaming charges.

Coverage on Phuket, Krabi, Phi Phi and Samui

Phuket

Phuket is one of the best-covered regions in Thailand. There is steady 4G — and 5G in many areas — around Patong, Kata, Karon, Phuket Town and the airport.

Only in the island's far northern reaches and at some high viewpoints can the signal weaken.

Krabi and Railay

Krabi Town and Ao Nang have excellent coverage.

On the longtail boats over to Railay Beach, however, things change. The further the boat gets from shore, the more the internet can cut out. Once you reach Railay, the signal returns to normal.

Koh Phi Phi

On Phi Phi, the main tourist area of Tonsai Village has good coverage.

But as you climb toward the viewpoint, on the quieter beaches and at famous excursion spots like Maya Bay, the signal can drop off quickly or disappear entirely.

Koh Samui and Koh Tao

Koh Samui is one of the most stable places for internet among the southern islands. Along Chaweng, Lamai and the main ring road, the connection runs almost without interruption.

On Koh Tao, coverage becomes more patchy the further you get from the main beaches. It's normal to go without internet for a long stretch once the dive boats leave the shore.

Why doesn't the internet work at the Full Moon Party?

At the famous Full Moon Party on Koh Phangan, the problem isn't mobile coverage.

The problem is that tens of thousands of people are using the same cell towers at the same time. As a result:

messages are delayed;
photos won't send;
maps won't load;
internet speed slows dramatically.

No eSIM can fix this. The cause is simply an overloaded network.

Before you head to the party:

save your hotel's location on the map;
screenshot your route back;
agree on a meeting point with your friends in advance.

That way, even if the internet fails, your plans won't fall apart.

Why does the internet cut out on the ferries?

In Thailand, most of the internet dead zones happen out at sea.

The most common ones are:

the Ao Nang – Railay longtail boats;
the Phuket – Phi Phi – Krabi ferries;
the Samui – Phangan – Koh Tao route;
dive and snorkelling boats;
excursions to the Similan Islands.

Once you're away from the harbours, the signal can vanish completely for a while. As you approach the shore again, it comes back.

For that reason, before you set off:

download offline Google Maps;
save your ferry tickets to your phone;
screenshot your hotel addresses.

That way, even without internet, your trip carries on without a hitch.

How much data do you need for Thailand?

Most tourists use less data than they think.

Rough usage:

WhatsApp voice call — about 0.5 MB/minute
Video call — roughly 10 times that
Google Maps — just a few MB per hour
Messaging and sending photos — uses very little data

If you'll mostly be using maps, messaging and sharing the odd photo, 3–5 GB is enough for a 7–10 day trip.

If you video-call every day, or watch TikTok, Instagram Reels or YouTube, a 10 GB or larger plan will be more comfortable.

Set up your eSIM before you fly

The easiest option is to install your travel eSIM before you leave home, while you're on Wi-Fi.

Once the profile is added to your phone:

your physical SIM card stays in the phone;
you keep using your own phone number;
your WhatsApp account doesn't change;
your bank OTP codes still arrive on your original number.

Just switch your internet connection over to the Thailand eSIM and turn off data roaming on your main SIM.

That way, the moment you land in Phuket or Bangkok, you can start using the internet without hunting for a shop.

Browse Thailand eSIM plans and, by setting it up in a couple of minutes before your trip, land in Thailand already online.

Frequently asked questions

Will the internet work on the ferry from Phuket to Phi Phi?: It will work as you leave the harbours and approach the islands. In the middle of the crossing, out on the open sea, it's normal to have no signal for a long stretch. That's why it's best to download your maps and tickets in advance.
Which network is better for the Thai islands?: On the southern islands, AIS usually has the widest coverage. TrueMove H and dtac work very well in the cities, but on the smaller islands AIS is considered the more reliable choice. A good travel eSIM automatically connects to the strongest available network.
Why does the internet weaken during the Full Moon Party?: The problem isn't coverage. Because tens of thousands of people use the same cell towers at once, the network becomes overloaded. That's why internet speed drops and messages can be delayed.
How many GB of data do you need for a week-long island trip?: For maps, messaging and photos, 3–5 GB is usually enough for a 7–10 day trip. If you video-call or watch video every day, a 10 GB or larger plan makes more sense.
If I use an eSIM, will I keep my own phone number?: Yes. A travel eSIM works alongside your physical SIM card. Your own number stays active, your WhatsApp account doesn't change, and you receive your bank OTP codes just as before.
When should I set up the eSIM?: The best time is before your flight, at home on Wi-Fi. Once you arrive in Thailand, switch your data connection over to the eSIM and start using the internet within a few minutes.