[annapurna]

Allan,

This may show how much of a "country bumpkin" I am, but have you tried lakes, resevoirs, or hot springs? The former tend to be well over 9 feet deep just by their very nature, while the latter often have fairly elaborate therapy pools, depending on the locale. If these don't work, would the ocean be an option? If you wanted to try a calm ocean setting but lived in a cooler climate, perhaps a thick, well-fitted wetsuit would be an option since it would provide both warmth AND flotation, allowing you to just jump in and run in place, so to speak. Needless to say, the typical "surfing beach" wouldn't be a good idea.

I've got to admit that warm water can really helps. I swam laps at a local hot-spring last week (pool temps around 95 degrees F), and my back felt about as good as it had in months - even after 3 miles! There's a good guide to public hotspring in the northwest and southwestern US - could find links if you'd like.