I was going to tell you to look at Scuba Earth, but wow, nobody in that neighborhood, no dive shops, members, pros and only one dive site listed :(
Did you get certified in Oslo? You should tell your dive shop to become a member, it’s free and list some dive sites to make Oslo look more inviting to divers.
My wife and I have talked about a cruise thru there to explore my 31% Scandinavian roots and I usually do dives on these cruises.