The main station in Bangkok is Hua Lampong, which serves all four major lines. The first line runs to Chiang Mai via the Central Plains. A second, which later divides in two, runs to Nong Khai and Ubon Ratchathani in Northeast Thailand. A third connects Bangkok to the Eastern Seaboard and Cambodia, and a fourth runs down the peninsula to Malaysia. However, Thon Buri Station in Bangkok Noi is the principal departure point for trains to the South. It also has lines to Kanchanaburi and Suphan Buri.

Train services are labeled Special Express (the fastest), Express, Rapid (slower than Express), and Ordinary. Travel times, even on Express trains, can be longer than by road. The trip from Bangkok to Chiang Mai, for instance, takes 11 to 13 hours.

First-class coaches (available on Express and Special Express trains) consist of individual cabins with air-conditioning. Second-class coaches have reclining seats and a choice of fans or air-conditioning. Sleepers in this class have individual seats that are converted into curtained-off beds at night. Toilets (there should be at least one Western toilet) and washing facilities are at the end of coaches.

Most tourists find that second class is comfortable enough for long distances and far more relaxing than a bus journey.

Third-class coaches have wooden benches, each seating two or three passengers: they are cheap but not recommended for long distances. Most trains are clean and well maintained. Uniformed vendors stroll up and down the aisles with refreshments, and buffet cars are attached to trains on long-distance routes.

A train timetable in English is available from Hua Lamphong Station in Bangkok. Be aware that trains at peak periods (weekends and holidays) can be sold out days in advance. Hua Lampong has an advance booking office with English-speaking staff. Some travel agents will also book train tickets.

Fares depend on the speed of the train and the class of the carriage. A second-class ticket between Bangkok and Chiang Mai is about 280 baht , with supplements of around 50–80 baht  for Rapid and Express services. Shorter trips, such as from Bangkok to Ayutthaya, cost anything between 15–120 baht .

Tourists can also buy 20-day rail passes. These cost 1,000–2,000 baht . Information about these is available from Hua Lampong Station.

Long-distance buses run from the Eastern (Ekamai), Northern (Morchit), and Southern (Pin Klao) bus terminals in Bangkok.

Most provincial capitals can be reached direct from Bangkok. Large cities such as Chiang Mai, Phitsanulok, Khorat, and Surat Thani also act as transit hubs, with both long-distance and local connections. Buses can be faster than trains: Bangkok to Chiang Mai takes about ten hours. Vehicles are air-conditioned, with a toilet, reclining seats, and plenty of leg room. “VIP” buses have the best facilities, including free refreshments served by a stewardess. Overnight services are popular, though they can get rather chilly – blankets should be provided.

Fares for long-distance bus trips are similar in price to second-class train tickets. “VIP” buses are at the top of the price range. Book well in advance through a travel agent or at the bus station if traveling on the weekend or during a public holiday. Otherwise, just turn up at the coach station at least half an hour before departure. Tickets are always bought as one-way.

The government bus company is called Bor Kor Sor  (BKS). Its buses are frequent, relatively reliable, and the cheapest form of transportation in Thailand. Booking is rarely necessary. On many buses simply pay the driver or conductor. Almost every town will have a BKS terminal. The non air-conditioned (rot thamadaa)  buses are the cheapest and slowest, and they stop almost everywhere along the way. Air-conditioned (rot aer)  local buses do not necessarily provide blankets, so take a jacket or sweater, especially at nighttime.

Traveling on provincial buses is a good way to meet local people and reach many villages and sights. Beware, though, that refreshment and toilet stops may be infrequent, the buses may be in a poor state of repair, and the road skills of drivers will vary. Local services are nearly always slow and crowded. Back seats are reserved for monks, so be prepared to move or stand. Women should avoid sitting next to monks.

Scheduled ferries are always erratic, since their service is dependent on the weather conditions. Regular services are available to Ko Samui, Ko Pha Ngan, and Ko Tao from Surat Thani. Ko Phi Phi is served by ferries from Phuket and Krabi. Smaller islands have less regular services – sometimes just a makeshift ferry run by local fishermen. Travel agents will be able to give you rough timetables, but these may be dependent on filling enough seats in the boat. Many services stop in the rainy season.