Getting there and around
Thailand is one flight, then a network.
Two Bangkok airports, a domestic flight map that reaches every region in about an hour, overnight trains worth taking for their own sake, and ferries that set the islands' rhythm. Get the gateways straight and the whole calendar opens up.
Arriving
Suvarnabhumi (BKK) is the main international gateway, east of Bangkok: the Airport Rail Link runs to Phaya Thai in about half an hour, taxis and ride-hailing apps cover the rest. Don Mueang (DMK), the old airport in the north of the city, handles most low-cost and domestic flying, with a rail link to Bang Sue and buses into town. Phuket (HKT), Chiang Mai (CNX), Krabi (KBV) and Koh Samui (USM) take international flights of their own, so a beach or northern trip does not have to route through the capital. Before you land, complete the Thailand Digital Arrival Card (TDAC) online in the three days before arrival: it replaced the paper arrival card and airlines and immigration both expect it done.
Getting around Bangkok
The BTS Skytrain and MRT metro cross the city above and below the traffic, and the river boats on the Chao Phraya are the pleasant way to reach the Grand Palace and the old town piers. A Rabbit card covers the BTS; the MRT runs its own card and contactless bank cards work at its gates. Taxis are metered and cheap when the meter is on: insist on it. Ride-hailing apps (Grab above all) are the fallback everyone uses.
Trains worth the trip
The State Railway's overnight sleepers are the classic routes: Bangkok to Chiang Mai through the hills, and Bangkok to Surat Thani for the island ferries. Book sleepers ahead in festival weeks; they sell out at Songkran and Loy Krathong. Day trains to Ayutthaya and Kanchanaburi are slow, cheap and part of the experience.
Flying inside Thailand
Domestic flights are the long-leg answer: Bangkok to Chiang Mai, Phuket, Krabi, Surat Thani and Hat Yai all run about an hour, several times a day, on full-service and low-cost carriers. Koh Samui's airport is owned by Bangkok Airways, which keeps its prices above the mainland routes. Book festival weeks early, and remember the islands add a ferry or a bus-boat joint ticket at the far end.
Islands and ferries
The Gulf islands (Samui, Phangan, Tao) sail from Surat Thani and Chumphon, with Lomprayah and Seatran the main fast-boat names; the Andaman side (Phi Phi, Lanta, Lipe) sails from Phuket, Krabi and Trang. Timetables shrink in the green season and the last boat of the day sets your plans: never schedule a flight the same morning as a ferry off an island.
Search airport transfersvia Klook
Search Thailand eSIMsvia KKday
The luggage trick
Bangkok has luggage delivery services that move a suitcase between the airports, hotels and malls the same day, and couriers will ship a bag to your next city cheaply. Travelling light between festival stops, with the big bag following, is how the locals do long trips.