Yes, what you need to find or create is a shape file representing the whole world. The you can union it using the shape file that contains the continents. After the union, you will need to delete the portion that came from continents. In ArcGIS, use ArcToolbox > Analysis Tools > Overlay > Union.
If you have ESRI software, you have a feature class called WORLD30.shp that you can use for the entire world. You also have a feature class called continent that you can use for the continents.