Boating in Poland - any useful sites?

We're thinking of going boating on the lakes in Poland. Can anyone
point me at useful sites with information about requirements, maps of
navigable canals and rivers, etc.

My Polish is not quite non-existent but sites in English would be
better!

I have found lots of places to hire boats from in the Mazurian lakes
but finding further information (as above) seems more difficult.


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Chris Green