US$ Dollars is the currency used in Ecuador and the Galapagos.
There are NO banks on Isabela. It is important to bring sufficient cash for the duration of your stay on the island. Bring small bills (1, 5, 10$) – many places will not (be able to) accept or change large bills.
However the neighboring island of Santa Cruz El Banco del Pacífico is open Monday to Friday 8:00 - 3:30; Saturday 9:30 -12:30. The bank cashes travelers checks; however expect rates a bit lower than on the mainland. Personal checks are not accepted. The bank's ATM accepts only Cirrus, Star, and MasterCard (7 am - 11:30 pm). Unfortunately, the ATM is down more often than the bank would like to admit. If this is the case you can request a cash withdrawal with your MasterCard (but not with a Cirrus card) from a bank teller. Money transfers are possible; however they take 4 to 7 days. Faster but more expensive is a MoneyGram with American Express. With a MoneyGram you will receive your dinero within hours -- if the phone lines are working. You do not have to be a card holder to use a MoneyGram.
There are two banks in San Cristobal: Banco del Pacifico and Fomento. For ATM access students should use cards that have either a CIRRUS or Mastercard symbol. Cards with the Visa symbol are not usually accepted by ATMs in San Cristobal. Instead, students with a Visa card will have to go the bank and ask for a cash advance, which has a fee of 4% of the total value of the transaction. Traveler’s Checks can be changed by banks in San Cristobal, with a fee of $5 for the total transaction. Traveler’s checks from American Express work best.
Credit cards are only accepted in the hotel Casa de Marita in Isabela. On the island of Santa Cruz Mastercard, Visa, and American Express are usually accepted (only in higher-end places). In general, Mastercard is the most widely accepted card both in the Galapagos and on the mainland.