Holbox Island is a quiet little place, where some services are not yet consistently available here, as in the case of banks and ATMs.
Banks not yet definitively established in Holbox but ATMs yes.
Many of the businesses on the island accept payment in dollars and euros, but not all, so it is recommended to stop an exchange before arriving here . Some hotels may offer money exchange services , but with lower rates.
If you come from Cancun, do not forget to stop at the bank of your choice before you hit the road or if you coming from Merida you can make a stop at Valladolid or Tizimin, depending on the route that you choose . In holbox is dificult to find a store with credit card terminal.
There are several restaurants that accept credit cards but not all. Only limited services may be paid by credit card.
You can also change currency in the exchange houses at Cancun airport. It is preferable to take Mexican pesos.