Jesper Larsson listed the swimming pond as one of his 2009 Design Top 5 trends on MoCo Loco. Still, finding a local expert and vendor in Canada or the United States for these chemical free swimming pools may be hard.
You must be aware that a natural swimming pond requires slightly more maintenance in time than a regular swimming pools. If you are interested by a natural swimming pond, read first those articles:
I dug a few suppliers in Canada and the United States. They are probably more.
Another option: A Salt System
If you are ready to go with a biological cleaning systems to clarify and purify the water, there are easily accessible alternatives to a chlorine system. My brother went for a salt system and he loves it. Unfortunately, converting an existing pool can be costly as it requires non-corrosive pipes and to change your equipment. The salt system eliminates the chemical smell, but most importantly it will not make your eyes red and will not dry your skin.