We did this cruise last summer. You do have to exchange money for a few countries but the ship will let you know what to do. You can exchange it right on the ship. Depending on what excursions you do in each country they will make recommendations. A lot of countries use the Euro and some will take the dollar. Just be careful in St. Petersburg, there is a lot of fake dollars going around. They will recommend to spend the ones you receive while you are still in port just in case the are counterfeit.