The leisure and tourism association, Swiss Friends of Nature, has marked its centenary on Saturday with a celebratory event, a new book and a special stamp.
Rooted in the workers' movement, the federation has evolved into a tourist organisation but retains its social and ecological focus.
In recognition of the organisation's contribution to society, Swiss Post has brought out a special stamp and the Basel historian Beatrice Schumann has produced a book on the movement and its members.
The anniversary itself was marked on Saturday with a circus performance in Zurich.
The first Friends of Nature group was set up in Austria in 1895 with the aim of giving working people the opportunity to enjoy nature. Swiss sections were opened up in 1905 in Zurich, followed by Bern, Lucerne and Davos.
The idea was that the countryside, and the fresh air of the mountains in particular, should be accessible to town dwellers of limited means.
In Switzerland the Friends offered workers free-time activities such as hiking, climbing, skiing and mushroom picking.
They also built holiday houses in the country, the first one being erected in 1912 on the Säntis peak in northeastern Switzerland.
In the interwar years the Friends pioneered "tourism for the masses", offering holidays at attractive prices.
Affiliated to the International Friends of Nature, the Swiss branch has grown into a large organisation with 24,000 members and 170 sections.
It now owns 90 holiday houses throughout Switzerland, providing inexpensive accommodation to 140,000 people a year.
Today the organisation's focus is on environmental protection and sustainable use of the countryside. It is involved in creating footpaths and cycle paths and in training volunteers to teach courses on winter sports, hiking and ecology.
swissinfo with agencies
The Swiss Friends of Nature was founded in Zurich in 1905.
Today the organisation boasts 24,000 members and 170 sections.
It runs 90 holiday houses, mainly in the Jura mountains and the Prealps, which accommodate 140,000 people every year.
On Saturday the Swiss Friends of Nature association celebrated its centenary in Zurich.
It marked the day with a special circus performance, followed by a gala dinner.
A book has been written on the history of the organisation and a special stamp produced by Swiss Post.