As American cruisers and tourists know, our Am Ex is null in Cuba and cash
is king. King with a penalty.
The Cuban Pesos Convertible (CUC) is the standard currency and their is another national currency. One CUC is worth $25 national pesos.
One CUC is worth $1 USD, $1 Canadian Dollar and $1 Euro. That said, there is a fee for converting. With $1 USD you'll receive $.87 CUC. For all other denominations, that fee is 3%. The American dollar comes with a 10% penalty.
That said, ask around. We were able to exchange for $.87, $.90, and $.95. Some rules just get made up as you go.