Thailand’s transport system is excellent compared with much of Southeast Asia and has the added bonus of being a cheap way of getting around.
To get around via air you can choose from a variety of domestic airlines including budget options like Thai Airasia, Lion Air, and Nok Air. The national carrier is Thai Airways and air travel in Thailand is widely considered safe, particularly compared to neighboring countries like Indonesia.
By boat or ferry
In order to get out to the islands you will need to take a ferry, smaller fast boat, or speedboat, and there have been a number of accidents in recent years so check the boat you will be travelling on before you purchase a ticket and don’t get on if it is obviously overcrowded.
By train or bus
Also remember that most of the country is serviced either by the train or bus network meaning that you can pretty much get anywhere you want to go, even places that are off the beaten track. In bigger cities there are buses, tuk tuks, taxis, and even a metro system in Bangkok.