Internet & SIM cards on Koh Tao.

Condos are essentially nonexistent on Koh Tao, so most long-stayers rent a room or bungalow through a dive resort or guesthouse where fibre wifi is already connected and simply included, rather than signing up for a home line themselves. Speed and reliability vary a lot by property — ask to see a speed test before committing if you need to work remotely, since older buildings on the east-coast bays can lag well behind Mae Haad and Sairee.

True and AIS both run fibre to parts of Mae Haad and Sairee Beach, the island's two main hubs, and a private line is realistic if you are renting a longer-term house or staff apartment rather than a resort room. Plans run broadly similar to elsewhere in Thailand — roughly 500–900 baht a month — though installation can take longer than on the mainland since equipment and technicians often come over by ferry from Koh Samui.

Ao Leuk, Tanote Bay, Hin Wong Bay and Freedom Beach sit across steep, partly unpaved roads from the west coast, and fixed fibre is patchier out here — several resorts lean on 4G routers or satellite-backed connections instead of a wired line. If you are renting in one of these quieter bays and need dependable work-from-home internet, confirm the exact setup with the landlord before signing rather than assuming fibre is available.

If you do want your own line in Mae Haad or Sairee, bring your passport and lease; a technician installs a router within a few days for an already-wired address, though anything requiring a fresh line pulled in can take noticeably longer than on the mainland because parts and crews often travel over by boat. Ask your landlord first — many long-stay rooms and staff apartments already include wifi in the rent.

AIS generally has the widest and most dependable coverage on Koh Tao, including further out to sea on the boat rides to dive sites, which matters if you want to stay reachable during surface intervals. True and dtac (now merged with True) both work well around Mae Haad and Sairee Beach but can thin out faster than AIS on the steeper east-coast roads and offshore. Most instructors and long-stay divers default to AIS for this reason.

Prepaid (top-up) SIMs are by far the more common choice on Koh Tao, since most of the island's foreign population — dive instructors, divemasters and seasonal staff — are on shorter-term visas and move around; buy one over the counter with your passport, add credit, and pick a data package, no contract required. Postpaid plans exist and can be cheaper per gigabyte, but the paperwork (proof of address, a longer-stay visa) is a harder fit for transient dive-industry life.

Shops around Mae Haad's pier sell 'Tourist SIM' packages — typically 8, 15 or 30 days of generous or unlimited data — convenient if you're here for a short certification course. If you're staying for a season or longer as an instructor or divemaster, a standard prepaid SIM with a monthly data package (often 300–600 baht) works out far cheaper than repeatedly renewing tourist bundles.

AIS, True and dtac all support eSIM on compatible phones, activated in-store in Mae Haad by scanning a QR code. Since Koh Tao has no airport, most arrivals connect via Koh Samui (USM) or Chumphon and then take a ferry — an international travel eSIM (Airalo, Holafly and similar) lets you land already connected for that leg, though a local Thai operator plan is cheaper once you're settled on the island.

Mobile signal generally extends well out to Koh Tao's most popular dive sites — Chumphon Pinnacle, Southwest Pinnacle and the HTMS Sattakut wreck are all within range of AIS's network — though signal drops the moment you're underwater and can be patchy on the boat itself depending on distance from shore and weather. Most dive shops treat the boat ride as offline time by default and check messages once back at the pier.

Koh Tao has a much smaller cafe and coworking culture than Koh Phangan or Koh Samui, concentrated mainly in Sairee Beach and Mae Haad. Most remote workers pair their resort or private wifi with a mobile data package as backup — if the wifi drops during a call, tether to your phone rather than lose the connection. See our cafes & wifi guide for the specific spots with reliable power and internet for a work session.

Topping up is easy: use the operator's app (myAIS, TrueID, dtac app), buy a top-up at a 7-Eleven or Family Mart in Mae Haad or Sairee, use a top-up kiosk, or dial the USSD code on your SIM's starter pack. Once you have credit, activate a data package through the app or a short code and set auto-renew so it refreshes each month without a trip back to the shop.

The most reliable spot is an operator shop or authorised dealer near Mae Haad's pier, where staff can help with registration, eSIM activation and any postpaid paperwork. 7-Elevens and minimarts across Mae Haad, Sairee Beach and Chalok Baan Kao sell basic prepaid SIMs. Thai law requires SIM registration with a passport, so bring it with you wherever you buy.

Expect roughly 500–900 baht a month for a private fibre line where available, though many long-stayers pay nothing extra since wifi is bundled into resort or staff-room rent. A mobile data package runs about 300–600 baht a month (unlimited plans at the upper end), and a basic prepaid starter SIM costs around 50–200 baht before data. All in, a connected long-stay diver on Koh Tao typically spends 300–900 baht a month on mobile alone.

Do I need to set up my own internet on Koh Tao?

Usually not. Most long-stayers rent through a dive resort or guesthouse where wifi is already connected and included in the rent. A private True or AIS fibre line is realistic in Mae Haad or Sairee Beach if you want your own connection, but coverage and installation timelines are patchier on the quieter east-coast bays — always ask your landlord what's actually available before assuming.

Which mobile network has the best coverage on Koh Tao?

AIS generally has the widest and most dependable coverage on the island, including further out to sea toward the main dive sites, which matters for instructors and divemasters who want to stay reachable between dives. True and dtac work well around Mae Haad and Sairee Beach but can thin out faster on the steeper east-coast roads.

Should I get a prepaid or postpaid SIM on Koh Tao?

Prepaid is by far the more common choice, since most of the island's foreign population is on shorter-term dive-related visas and moves around. Buy a prepaid SIM over the counter with just your passport and add a monthly data package — no contract or credit check needed.

Can I use an eSIM on Koh Tao?

Yes. AIS, True and dtac all support eSIM on compatible phones, activated in-store in Mae Haad. Since Koh Tao has no airport, most travellers arrive via a Koh Samui or Chumphon flight plus ferry — an international travel eSIM like Airalo or Holafly can keep you connected for that leg before you switch to a cheaper local Thai plan.

How much does internet and mobile cost on Koh Tao?

A private fibre line runs about 500–900 baht a month where available, though many long-stayers get wifi included in resort or staff-room rent. A mobile data package costs roughly 300–600 baht a month, and a basic prepaid starter SIM is about 50–200 baht before data — a connected long-stay diver typically spends 300–900 baht a month on mobile alone.