Can anyone advice me the best place to go for white water rafting in Thailand?

How much will it cost?

try a river , or a lake if you're hungover

You can find good ones in Nan province.

In BKK you may be able to find some info on how to get there (travel agents, etc).

There is a water rafting community up there, all BKKians.

I hear the best time is July - Sept.

Good luck and post back if you ever make it up there.

The Kok river in Chiang Rai, and the Pai river in Pai, Chiang Mai Province (or in Mae hong sorn Province?) has pretty good river rafting (mostly) during the rainy season. The Kok river also has floating bambo huts which can be floated from Thaton to ChiangRai town, an overnight trip.

A google search came back with this page of links http://www.google.com/search?hl=en&q=thail...G=Google+Search

A Thai friend of mine likes to go kayaking in Petchaburi province, I think up near the Kaeng Krachan Dam เขื่อนแก่งกระจาน . He's invited me along a couple of times, but we haven't been able to set a date yet. I suspect that it wouldn't qualify a "white water" by Western standards though.

ive done bamboo rafting once in chiang mai and have to say its such a massive experience. have a go

If you're in BKK you could try Khao Yai NP. You can easily do it as a day trip.

Go to the HQ in the park and at the restaurant you will see a book with photos explaining tours, treks, rafting, safaris, prices etc.

You may find some more info with a google search.