Nakukymppi!

[John P]

Wikipedia:
Nakukymppi is a nude sport event in Finland, held in the municipality of Padasjoki one week before Midsummer every year.

The idea is to run or walk 10 kilometres naked. Participants wear only shoes, socks and headwear. Women wear a top if their breasts are shaking too much. It has been held annually since 2003. It usually draws about 100 to 150 participants, of which one-tenth to one-fifth are women. Even though the event isn't organised by naturists and not only for naturists, half of the participants are naturists.

The event is organized by Mr. Aarne Heino together with local village community.

https://endlessvideo.com/watch?v=tdYDeHOb-hI

[Greenbare Woods]

The more often people are encouraged to be naked in public the better.   More people get an experience being naked.  More people get an experience of seeing naked people.  Nobody is harmed by the experience and that is another experience. 

They need to lose their shoes.  Feet love being naked.

[BlueTrain]

The first thing I thought, mainly because the post was made in early winter, was that it was a winter event. But it isn't, of course, although it would have been a lot more interesting. A sort of variation on the polar bear club thing.

[MartinM]

The more often people are encouraged to be naked in public the better.   More people get an experience being naked.  More people get an experience of seeing naked people.  Nobody is harmed by the experience and that is another experience.

They need to lose their shoes.  Feet love being naked.

I agree, but they need to get off the road and on to paths and more natural ground. Stony, gritty tracks are not much fun to run on barefoot for any distance.

[nuduke]

Interesting stats, John P.
Half of the participants not being naturists suggests (at least in Finland, but I hope universally) that there are many people out there who want to get naked if the circumstances allow it (e.g. on holidays and in events).  As many surveys suggest, there really are many more naturists than those who identify themselves as one.
John

[BlueTrain]

The thing is, nobody owns nudism, so it can be whatever you think it is. And by the way, stone is natural.