I have have my reasons or purpose, what are yours in your paddling world.
Brian
cheese…
Mine slices a mean smoked gouda, I hope thats all I ever need it for. 
Cheese Whiz
save knife for the sausage
Brian
Fruit
I have a partial denture in the upper front (Hockey injury) & I have to cut up most hard fruit to eat it.
I also use it to unjam other paddlers’ skegs, cut things in camp, etc. A good knife is indispensible.
And I also hope I never have to use it for it’s main intended purpose. But if I do, it’s right under my nose.
Wayne
“Rescue” a power boating fisherman
A couple of years ago while out on a day paddle I came across a fisherman in an anchored power boat. I initially tried to give his craft a wide birth, but he called me over. He had snagged his anchor on an obstruction in about 25’ of water. He sheepishly admitted that he had no knive in his kit for cutting his boat loose. Did I happen happen to anything on me? Well, by golly I knew there was some reason I carried this blade on me. Either for this purpose or a shark attack.
Safe Paddling, Joe
River knives …
Useful when working with ropes…
A tangled line, or a line under tension may entrap, or endanger someone, and on occasion, the quickest & most effective solution is to cut the line.
I do whitewater in an OC1. If I, or one of my paddling buddies has an “out of boat experience”; gets entangled in their canoe painter, their flotation bag’s lace kit, a thrown rope, quick tether on a rescue pfd, haul system, or any other type of entanglement, I don’t want to wait till someone can get a knife from “somewhere”?
I also have one on my pfd due to my involvement on a search & rescue team.
Most of the time it gets used for cutting cheese, spreading peanut butter,etc. I’ll be happy if that’s the only way mine ever gets used, but I’d rather have it & not need it, than need it & not have it.
Note: There are possible hazards to cutting a line under tension.
BOB
mostly for
entanglement issues. I use a paddle leash , anchor w/ rope and a painter. Don’t want to be tangled and underwater for too long. Also good for camp chores.
mostly
just to look cool
Swedge , to be really cool
carry it in you teeth.
Darned handsome…
woman, and she’s got all her teeth! 
ON PFD
Attached to your PFD. Not bundled somewhere in your kit.
can’t be to careful
Keep that knife close to the lip gloss
Brian
Organizationally challenged
I’m one of those who can scatter gear like crazy. With a knife on my vest, I can visually asure that I’ve got it and can find it quick. After a recent river mishap my whistle is also right there handy.
Fishhooks on droplines and trotlines are common in lots of areas I paddle. My dad, who was ordnarily a man of good judgement, once managed to get snagged in the hand by a trotline we were passing on the Nueces River. He got it loose on his own after a little group panic, but I’ve religiously carried a knife handy ever since.
Darned good looking woman with
teeth AND a boat! Jill, do you clean fish?
I don’t tow without a quick release
– Last Updated: Jul-23-04 3:20 PM EST –
and a cutting tool. Sea ships are the best but I admit I use a 1.75 inch blade on a 3.00 inch handle on my pfd. Lagriffe WWR; one sharp piece of stainless steel. I use it for nothing else but safety and an occasional demonstration or what a sharp knife is really like. One day I will retire it and get another pair of sea ships.
No taiwanese knockoff can compare with it for performance. NO factory made knife can compare with it for sharpness, unless it has been resharpened by an expert.
I took my knife off my PFD because
it kept snagging when I was practicing paddle float re-entries. Now I paddle a canoe.
My primary excuse for carrying one…
is entanglement in a line. Although it also has come in handy for cutting down the lures and hooks I find suspended at eye level over the edges of the water, and for the occasional cheese snack-(I prefer Shelburne Farms extra sharp cheddar)
~Glenn
A number of reasons…
1) Entanglements
2) Injuries (cutting away clothing or bootlaces)
3) Camp chores
4) Food or wood gathering
5) Eating
6) Stickin’ burning logs to “re-adjust a crumbling fire”
7) Cooking
8) opening food packages or cans
9) Snakes & other “bothersome” critters
10) Playng Mumbly-peg
The list can go on & on for why to carry a knife while paddling/camping.
Paddle easy,
Coffee
Importance Noted
lessons and reminders learned by the many comments and understand the many possibilites, some remote but unusual and sticky situations one can get into requiring a handy reach to a pocket knife.
Brian