As a Norwegian citizen, you do not need your passport if you are traveling between the Nordic countries. This according to an agreement on passport freedom, but police recommend that you bring valid identification.
The reason is that you as a traveler may be asked to provide identification to carriers when boarding a plane, train, bus or boat, also at check-in accommodations. Here travelers must check which requirements for credentials apply to their situation. Some carriers only accept passports as valid identification.
The credentials must include photo and date of birth, and must indicate the country of origin. Examples of identification are:
Bank cards with a photo and date of birth
Police recommend that those who have a valid passport bring this during travels in the Nordic countries, as this would ease the occourance of an eventual control.
Children traveling with their parents do not need credentials, It is suitable that the parents can show valid identification.
Children without valid identification on group travel, such as sports clubs and schools, should not be held back for inspection. It is sufficient that the leader of the group endorses who the kids are before they board. Police encourage children who have passports or other valid identification to bring this as it both shortens the wait and eases the control process.
The agreement on passport freedom applies to the countries of Denmark, Finland, Norway, Sweden and Iceland. That means you do not need a passport to cross the border between these Nordic countries. However, you may be asked to produce identification if internal border controls are introduced by one of the above countries, these below are common internal borders.
Ferry Travel and Øresund bridge
Should you as a Nordic citizen be traveling by ferries between Sweden, Denmark and Norway or over the Øresund bridge, you must have valid identification, as temporary border controls within the Nordic region exist for the time being.
Upon boarding the plane, train, bus or boat, or at check-in accommodations, the carrier or lodging require that they can legitimize you. You must examine the identification requirements that apply to your situation. The requirement can be a passport for one, several or all of your travel companions depending on your arrangements. You can check what is required when searching for information on their website, read travel information or contact them directly. Remember to ask for what they need and for whom. This is your responsibility when travelling.
Source: politi.no / Norway Today