What currency is used in Galapagos?
Since the year 2000, the official currency of the Galapagos Islands is the US dollar. It is best to use cash and cards, as traveller checks are not readily accepted. It's also best to bring smaller denomination notes - you won't be able to use anything bigger than a $20 bill.
There are 2 banks with ATMs in Puerto Ayora on Santa Cruz island, and an additional ATM at the Proinsular supermarket.
In Puerto Baquerizo Moreno on San Cristóbal Island, there is one bank with an ATM.
Most smaller shops, hotels and restaurants don't accept credit cards. Larger hotels and better restaurants may, but there is usually a 5-10% levy added to the bill for card payments. Where cards are accepted, VISA and MasterCard will work best. Very few businesses will accept American Express.
It's always wise to travel from the mainland with some cash. This prevents problems if you find your credit cards are not accepted for some reason, or if the local ATMs have run out of cash when you need one (with so few of them, this does happen at busy times of the year).