I use the Garmin Forerunner 610, that I initially brought for running/cycling. It is waterproof rated at IPX7, meaning it can withstand being submerged for 30 minutes at a depth of 1meter - so far I've had no probs taking it out Paddling. It's not as waterproof as the 310XT that is designed for triathletes & swimming - but it is a heap smaller and has a touch screen.
I don't think you need much more info than the basics when your actually doing an activity and the real value comes afterwards when you access your performance. Garmins are customisable so you can basically display whatever you want real time, but in reality its primarily, pace, distance, time & heart rate that count. Just added a post on another thread re 10km times about how I use the Garmin & Strava websites to do so - happy to provide more info if interested (or personal MSG my personal profiles on these sites).
I think you won't go wrong with either of these garmin options. If your are after a more detailed view of what these watches can do - checkout the DC Rainmaker Site. This guy is a GPS watch 'enthusiast' who writes very detailed independant reviews of them all.
www.dcrainmaker.com/2011/04/garmin-forerunner-610-in-depth-review.htmlwww.dcrainmaker.com/product-reviews