Most cruisers load up on a fair amount of cash before heading across the Gulf Stream to the Bahamas. Many out island merchants and fishermen do not take credit cards – even the entry fees usually need to be paid in cash – and ATMs are often not convenient, not functioning, or out of money. When you can use your credit card (or ATM card), you'll often be hit with a sizable transaction fee.
The Bahamas Parliament has enacted the Travellers Currency Declaration Act of 2014 which requires travelers to declare upon entry or exit if in possession of $10,000 or more in any currency. A "Travellers Currency Declaration Form" will need to be filled out and presented. Penalties for non-compliance can include forfeiture of the cash, plus up to a $2,000 fine on top of that.
The act is not yet in force but will most likely be by the end of the year – look for updates.
The act’s purpose is to combat money laundering, tax evasion, and for the Bahamas to comply with the USA’s Foreign Account Tax Compliance Act (FATCA) treaty.
Note: Both Bahamian dollars and U.S. dollars are accepted everywhere in the Bahamas and are equal in value (until you bring the Bahamas dollars back home and try to exchange them).