Make sure that the currency you are travelling with is in either cash US Dollars or cash Meticais. Visacard, Mastercard and Eurocard may be used to draw cash from banks, but not in shops or restaurants.
The Pemba Beach Hotel and CI Divers have card facilities. Rand bank notes can be changed at the banks for a good rate, but are otherwise not welcome. Restaurants, shops and hotels expect to be paid in Meticais, even if the price is quoted in US dollars. The Mozambique banking system imposes a 45 day delay on the clearing of travellers cheques, so traders refuse to accept them, but they can be cashed at a bank, for a fee. The "black market" in Pemba offers only marginally better rates than the banks, so is best avoided.