Take a bath in a natural swimming pool!
The first natural swimming pool was built in the early 1980s in Austria, in a private garden. Today, there are over 20,000 natural pools in Europe, 100 of which are actually public pools in Germany.
A natural swimming pool is divided in two areas:
1) The swimming zone is the area intended for swimming that resembles a conventional swimming pool.
2) The regeneration zone consists of a lined overflow pool filled with specific filtration substrate and flora. Plants used for water regeneration can be supplemented with decorative flowering species to create an attractive water garden environment. The biological processes that clean the water take place in this zone.
You can find out more information here: http://en.wikipedia.org/wiki/Natural_pool