There are two banks, Banco Nacional de Costa Rica and Banco de Costa Rica, they are across the street from each other, they have different hours with the Banco Nacional open from noon to 7PM. There are ATMs and you can usually get cash out of them but occasionally they run out over the weekend. I suggest you make arrangements to have cash accessible through a bank card and a credit card or a cash credit card in case one doesn't work in the ATM (some cards don't work, some do) and be sure to tell your bank and credit card company that you are traveling to Costa Rica so that they don't stop any transactions when you try to use the cards here. You cannot rely on most of the restaurants to take your credit card down here. Change your US$ into Colones as the bank, or take Colones out of the ATMs when you have an option of US$ or Colones. You will get a better exchange rate at the bank.