Norway has announced that from 15th July, 2020, visitors from UK will no longer be required to quarantine which effectively means that the green light has been given for cruising there too.
There are already cruises successfully operating in Norway, such as the twin-yachts of SeaDream Yacht Club who resumed cruises to Norwegian and Danish guests on 20th June.
However, the current FCO advice for UK travellers is to avoid any form of cruise travel, which would in effect mean travel insurance would be invalid at present for those wishing to join a cruise in Norway.
This advice, as of 13th July, is under continual review from the FCO, who are working closely with CLIA on the matter.