Your passport, valid for at least 6 months after your travel dates
Any tourist visas necessary (see additional info above)
Another form of identification, such as a driver’s license
Cash for meals, souvenirs, and tips
A camera with extra memory and/or batteries
Your smartphone, set to airplane mode to avoid roaming issues and save battery. Also consider a portable battery.
A money belt and/or decoy wallet
Note: for those traveling to the Amazon or Machu Picchu, bring a smaller bag that meets weight restrictions. From Cuzco to Machu Picchu, you are only allowed 5kg (11lb).