The official currency in Sri Lanka is Sri Lankan Rupee, and its currency code is LKR. The banknotes come in denominations of 10, 20, 50, 100, 200, 500, 1000, 2000 and 5000 rupees, and coins come in denominations of 1, 2, 5, and 10 rupees. The best way to get LKR is to withdraw cash from an ATM, but withdrawing money in an ATM can be charged heavily according to their policy, and your bank also may slap international transaction fees. Please, check with your bank for the costs before you depart.
Tourist class hotels, restaurants, and businesses widely accept Visa or MasterCard, but the use of AmEx is infrequent. They do not accept Travelers’ cheques in Sri Lanka. Almost every hotel do provide money exchange service; however, the rates are better in the banks or money changer outlets in the town.
There are still many shops and hotels that accept only cash. Small vendors may not accept foreign currencies. So, it's advisable to change some money at the airport first. There are banks and ATMs in major towns.
Most tours in Sri Lanka do not include admission tickets and activity fees, such as jeep safari, and you are required to pay in Sri Lankan money. So, please, consult your guide and plan how much you need cash for the following day.