If you exchange cash at a Cozumel bank, there is no fee; the Bank's profit is built into the spread between its Buy/Sell rate. When I was there in December, the Dollar was going up against the Peso, and when the exchange rate published in the Wall Street Journal was about 14.40 Pesos to the Dollar, I bought Pesos for cash at Scotia Bank, north end of the pedestrian walkway that goes north from the Plaza (just a few steps from Wet Wendy's) and got 14.05 Pesos to the Dollar. The only downsides to using cash to buy Pesos at a Bank in Cozumel are: (1) you must have your Passport with you; and (2) I believe that the limit on exchange is $500.00 US at a time. If you are thinking about getting Pesos from a US Bank before you leave, check what exchange rate they are giving you. I've checked a few times and Bank of America was offering an exhange rate which was worse than any of the Mexican Banks in Cozumel were offeing AND charging a fee for the exchange - not a good deal at all. The only real benefit to having Pesos before you get to Cozumel is that you save a few bucks on the Hotel Shuttle tickets - If I recall, the Shuttle was 96 Pesos (Airport to Casa Del Mar) or $10 US, meaning I saved about $2.50 by having the Pesos. Not worth it to go through the hassle of exchanging in the States, but I usually take 200-300 Pesos home with me and just stuff them in my Passport case for my next trip.