The local currency is Maldivian Rufiyaa but US dollars are also widely accepted across the Maldives.
ATMs in the Maldives only dispense Rufiyaa (often abbreviated to MVR or Rf). There are ATMs at Ibrahim Nasir International Airport but not on Maafushi so be sure to take enough money with you, although some guesthouses, shops and cafes accept major credit cards such as Visa and MasterCard.
There’s a Currency Exchange counter at the airport (outside the arrivals hall) but you must keep your receipt if you want to change any local currency back to a foreign currency again before your departure.
In Male you can find HSBC, Bank of Ceylon, State Bank of India and Bank of Maldives ATMs on Marine Drive which is the section of road adjacent to the sea facing the airport island.
You cannot purchase any Rufiyaa in advance outside of the Maldives and you cannot exchange it elsewhere once you’ve left the Maldives.