Most hotels and restaurants accept credit cards. Almost all of them with the exception of Zanzibar Watersports will levy a surcharge though. Most establishments also accept foreign currency in US$, British Pounds and Euros and travelers checks. For local shopping, you will need currency in Tanzanian Shillings. You will get the best exchange rate in Stone Town. PLEASE NOTE THAT THE ONLY ATMs ON THE ISLAND ARE IN STONE TOWN.