Koh Samui eSIM — plans from ₹299.00

Samui is one of the more charming arrivals in Thailand — the airport at USM is open-sided and garden-like, and you are driven to the terminal in a shuttle cart — but it is also one of the more expensive and limited, which is why a large share of visitors instead arrive by ferry from Donsak on the mainland after a flight or overnight train to Surat Thani. Both routes deposit you somewhere that then needs a taxi or songthaew along the ring road to Chaweng, Lamai, Bophut or Maenam.

SIM sales on the island are more likely to be a shop counter than a slick airport desk, and the ferry pier has none at all. That is the strongest argument for setting the eSIM up at home over Wi-Fi: it stays dormant, and the plan only begins when the phone first registers on a Thai network — whether that happens on the runway or on the boat approaching Nathon. Plans sit on the Thailand page.

AIS, True and NT all cover Samui's populated ring, with 5G around Chaweng, Bophut and the airport and solid 4G on the quieter south and west coasts. The interior — the road over the hill between Lamai and Nathon, and the waterfall tracks — is thinner, and a few jungle viewpoints drop out entirely. Offshore is where planning matters: the short hop to Koh Phangan holds a signal for much of the way because both islands are close and populated, while the longer run to Koh Tao and especially the Ang Thong marine park has extended stretches with nothing. Boat crews rely on VHF for that reason, not mobile data.

Download Samui, Koh Phangan and Koh Tao offline in one go, since you may hop between them and pier locations are easy to mistake. Data is needed here for ferry and speedboat bookings, scooter rental paperwork, weather during the late-year monsoon, and translation at the markets. Villa and resort Wi-Fi varies enormously by property and often will not reach a beachfront sala, so tethering a laptop from the eSIM is the dependable option. Full-moon and party nights around Haad Rin on Phangan congest the local cell heavily, so agree a meeting point in advance. Salt, sand and heat drain batteries, so bring a power bank. Compare with Krabi.