Contact your credit card company and let them know your dates in Cancun. Maybe activate international call option for cell phone.
dont forget a pen, to fill out the forms on the plane...thats annoying if you dont have one, you need your passport number on those forms, so i always write that down on something in my pocket, so you dont have to dig for your passport or even get up...just an idea.... have a great trip
YES - definatly let your card company know. Our 1st trip we did call ahead of time but after my wifes mother was in the hospital and a few pay phone calls and no dice the card didnt work until we were in Atlanta and were able to call the card company. Make sure you have 2 cards use only one in Cancun keep other just in case. If you card does get stopped DO NOT try to call the card company with that account, I couldn't get through with the card I used but did imediatly with the one I didn't. Both my cards were MBNA one Visa on MC. We had a credit card nightmare for about a month. Good luck