Getting a local SIM card on arrival is one of the best things you can do for your first day in Sri Lanka. It means Google Maps works from the moment you leave the airport, you can contact your guesthouse if your taxi is late, and you are not paying roaming charges for the duration of the trip. The process is simple and the cost is low.
Which network to use. Dialog is the recommended network for most tourists. It has the widest 4G coverage nationally, including in smaller towns and rural areas, and consistently performs best in independent speed tests. Mobitel is a solid second choice with similar pricing and good urban coverage. Both work reliably across the south coast. The smaller networks, Hutch and Airtel, are cheaper in some configurations but have patchier coverage outside the main cities.
Where to buy a SIM card. The easiest option is at Colombo Bandaranaike International Airport immediately after you arrive, before you collect your luggage or arrange transport. Dialog and Mobitel both have counters in the arrivals area. Staff will activate the SIM for you and confirm it is working before you leave the counter. Do not leave without checking this. Bring your passport as you will need it to register the SIM, which is a national requirement.
You can also buy a SIM at Dialog or Mobitel stores in any major town on the south coast. Galle, Matara, and Weligama all have retail outlets. The price is the same or slightly cheaper than the airport. If you land late and need data immediately, get it at the airport. If you can wait, the town stores have a wider range of plans available.
What it costs. The Dialog Tourist Pack costs approximately 1,449 rupees in total: 150 rupees for the SIM card plus 1,299 rupees for the tourist plan. This gives you 10GB of data valid for 30 days. A larger option giving 50GB for 30 days costs approximately 2,450 rupees in total. Both include local call credit. At current exchange rates, 10GB costs roughly $4 to $5 USD and 50GB costs around $7 to $8 USD. These are among the cheapest data prices in Asia.
eSIM option. If your phone supports eSIM (most phones made after 2020 do), Dialog offers a tourist eSIM that can be purchased and activated online before you arrive. This is useful if you want data working before you land or if you do not want to deal with a physical SIM. The price is comparable to the physical Tourist Pack.
What to expect from mobile data on the south coast. In Galle, Weligama, Mirissa, and all the main towns, 4G coverage is consistent and speeds are adequate for maps, messaging, and social media. In smaller spots like Hiriketiya, coverage can be intermittent indoors. In very remote beach locations, data may drop to 3G or be unavailable. If you are using a south coast base for remote work, supplement the mobile SIM with a dedicated coworking space that has fixed fibre internet.
One note. Some tourists report the airport SIM counters occasionally suggesting expensive add-ons or alternative plans that are not the standard tourist pack. Know what you want before you reach the counter. Dialog Tourist Pack at 1,299 rupees, or the larger 50GB plan if you need more data. Confirm what is included before you pay.