A flag state like for example Spain, has 7 different navigational zones for different types of boats with different types of certificates of registry.
Zone 1: Unlimited navigation or oceanic navigation area
Zone 2: Navigation between the coast and a line parallel from the coast of no more than 60 miles
Zone 3: Navigation between the coast and a line parallel from the coast of no more than 25 miles
Zone 4: Navigation between the coast and a line parallel from the coast of no more than 12 miles
Zone 5: Navigation 5 miles from the coast or harbour
Zone 6: navigation 2 miles from the coast or harbour
Zone 7: Navigation in protected waters (bays, port, and harbours)
And Spain is not the only European country that works with such navigational zones.
The International Certificate of Pleasure crafts (ICP) issued in the Netherlands however has no such restriction, what so ever. This means you can sail both inland waters within Europe, as well as cross the Mediterranean see to have a cup of coffee in Istanbul.
With an ICP you can sail any waters you like. Although the ICP document is formally only accepted within the EU, it is not uncommon that ICP holders also sail in international waters outside of the EU.