Check out this barefoot park http://barefootpark.eu/en/ It is really a park in the Netherlands that is designed to be walked with bare feet. For clothing they say "Sports or comfortable wear is recommended, so that you can easily roll up your trousers above the knee." and show a picture of legs covered with mud up to the knees. Has anyone heard of this park?
We've visited similar place to this one but in Bavaria, superb experience https://www.bad-woerishofen.de/die-gesundheitsstadt/parks-einrichtungen/kurpark/barfussweg.html
There are many parks built for barefoot walks in Czech republic as well. Have not see anything like that in the US yet. Wondering why.
Here http://www.barfusspark.info/ is a link to a site that collects similar parks in Germany and other countries (it also references Brunssum above). The English version of the site starts here http://www.barfusspark.info/en/index.htm . They also provide a Design Guide for barefoot parks at http://www.barfusspark.info/loesungsk/katalog_en.htm , so you can build your own barefoot park ... maybe an idea ;-) ... Regards, Christian