25 May 2021 Norway had updated travel regulations for visitors, that said:
Main rules for entry quarantine and stays at a quarantine hotel
Due to the COVID-19 pandemic, Norway has introduced strict entry restrictions for foreign nationals. Generally, foreign nationals who reside in Norway may enter the country, as well as EEA / Schengen citizens from countries with low infection pressure so-called “yellow countries”. Norwegian citizens always have the right to enter Norway.
You must therefore famiiarise yourself fully with the information found here:
Travel to Norway
Please note that there are exemptions that do not appear in the table.
For countries with infection rates: 25 per 100 000 inhabitants and an average of fewer than 4% positive test results during the past 2 weeks.
You can find information about the infection situation in Europe at the website of the Norwegian Institute of Public Health.
For example, for people arriving from countries outside the EEA/Schengen/UK must stay at a quarantine hotel for the entire quarantine period until a negative test result is produced after no less than 7 days.
Countries outside the EEA/Schengen/UK are designated as red or yellow, depending on the requirements regarding travel quarantine. The following rules apply to areas within the EEA/Schengen/UK which are subject to a duty to quarantine:
For travelers arriving from countries within the EEA/Schengen/UK with a lower rate of infection do not have to stay at a quarantine hotel. They must completed their quarantine at home or at another suitable places for quarantine. A low rate of infection means fewer than 150 new cases of COVID-19 per 100 000 people in the last 14 days and where no more than 4% of people tested have a positive test result.
Travelers from countries within the EEA/Schengen/UK with higher cases of COVID-19 than this allowance must stay at a quarantine hotels until they have a negative result from a test taken no sooner than 3 days after arrival. They must complete their quarantine at home or at another suitable place of quarantine and can end quarantine early following a negative test taken no sooner than 7 days after arrival.
Travelers from countries within the EEA/Schengen/UK with higher rate of infection must stay at a quarantine hotel until they have a negative result from a test taken no sooner than 7 days after arrival.