5 in Denmark, 3 in Norway and 10 in Sweden. No, not millions of people but the number of naturist resorts.
It's not just Scandinavia, we have also found a site dedicated to naturism in Iceland
Need to know - beaches
There is a slight difference between Denmark on one side and Norway and Sweden on the other side with regard to nude beaches.
In Denmark there is really no difference between a nude and a textile beach. It depends on whether the people using the beach happens to wear clothes or not.
In Sweden and Norway they have signposted (official) nude beaches or well defined stretches of beach (spontaneous) where you may be nude.
Scandinavian naturist portal