We are traveling to Thailand for the first time next month. We plan on spending time both in Bangkok and Chiang Mai. Some of the activites we are interested in include Kayaking and canyoning (near a waterfall). Is it safe to go in natural sources of fresh water, or should we pick some new activities?

Thanks in advance for any help.

Probably depends who you ask....some might say it is unsafe to go into fresh water at all...others have no problem. The risk is there, as in all fresh water. I caught giardia hiking the Green Mountain Trail in Vermont - didn't drink the water, just swam.

Posted too soon...
So, I would go ahead and go rafting, kayaking, canyoning, hiking...whatever (and I'm sure some others would refrain from going), but also be prepared with medicine or a plan to get it, know the symptoms of fresh water borne illnesses...do your homework about the area and what illnesses might be gotten there. Also, be sure you pick a reliable company to do adventure type activities with, as you want to minimize your risk of injury with well trained staff and top equipment.

Thanks KimJapan, I guess I have more research to do!

I think 'anywhere' in the world you swim in fresh water rivers or lakes you should take precautions and after being in water at least take minimal precautions washing down afterwards with some reliable anti-bacteria form of soap or something, I am no expert on this but it seems common sense, perhaps someone wise on this can suggest some product to use to 'wash down' afterwards, I am sure this applies pretty much 'anywhere in the world. Also seems sense to take ultra special care if you have any cut or graze on your skin.