The peso is Mexico’s official currency, but many places will take US dollars. Be aware that larger bills can be harder for vendors to break so bring plenty of $1’s, $5’s, and $10’s and know you'll get pesos back as change. If you go on an adventure way out of the main tourist areas, it will be best that you bring enough pesos along. Avoid changing too much money at the airport as you don’t get as good of a rate! Banks give the best rate but require you to take in your passport. There are plenty of ‘Cambio’ stations where you can trade US bills for Pesos around town, you'll also need a passport or driver's license to use these. ATM's are available in town, use common sense with these and choose one associated with a bank instead of one at a bar or randomly on a side street. You'll be charged a small service fee to use them and most limit you to $300 per day per card. If you run out of cash, this is definitely the best option!