Unlike countries like Cambodia and Burma US $$ are not used in Thailand. Everything is paid for in Baht.

However, do NOT change money before you arrive. The exchange rate is much better within Thailand and you can easily exchange your dollars for local currency when you arrive at the airport ....or get money out of an ATM if you prefer. There are zillions of ATMs in Thailand.

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“Not all those who wander are lost.” Tolkien.
Life is not measured by the number of breaths we take, but by the moments that take our breath away.