All these recent sharp discussion have got me rethinking my canoe camping kit. I have four quality folding knives in the 2.9"-3.5" blade range, which I frankly don't use a lot. But I don't have a good fixed blade knife, which would probably make more sense for canoe trips for MY particular needs and applications.
My applications do not include any fishing, hunting or food preparation, or any sophisticated whittling or woodworking.
My applications and needs would mainly be:
1. Occasional splitting of small diameter wood, as I carry a folding saw but no axe.
2. Occasional stripping and shaving of branches or small trunks into tarp poles.
3. Self-defense against man and beast. (Paranoid, yes, but I'm getting old.) So the knife should be a reasonable stabber.
4. Low maintenance, especially around water. I have little interest and great neglect for cleaning, sharpening and polishing.
5. Long enough to do the job but short enough that I can comfortably wear it. If I get a fixed blade, I would want to wear it in and out of the canoe.
6. Reasonable price. Fixed income here. I don't want junk but don't need a Rolls Royce.
I'm not necessarily looking for particular make and model recommendations--though they are welcome--but rather recommendations as to blade shape, blade length, blade steel, handle shape, handle material, and sheath type.
I've not read, and won't read, all 91 of the previous responses.
Cheapest "good knife" I've heard of is the Mora... a "Robust" model would do you well, probably around $15-20 (so requirement #6 is met). In order to split wood (your requirement #1), you really need something just a tad longer than you've listed... 4" is tough to baton with. 4.5" to 5" is easier. This would also make it a little heavier, which would be useful in filling the 2nd requirement, limbing saplings for poles. The Mora is pointy, and would stab someone just fine (#3). Can't remember what the steel type is, but I think the Mora is pretty rust-resistant. It comes in a plastic sheath, which prevents a lot of water from being held against the blade (like a wet leather one will). #5 is up to you... I can't tell you what you will find comfortable... My only suggestion here is maybe to modify the standard sheath with a "dangler" option. I dislike normal sheaths that simply slip onto my belt. I much prefer a dangler, which allows the blade to be tucked out of the way when sitting.
I personally normally use one of three knives, and I seldom wear them, preferring to carry them in my pack. The two I use here in LA (home) are a Fallkniven F1 and a Condor Nessmuk. The F1 is made of VG10 steel, a stainless laminate sandwiching a harder thin layer between two stainless softer layers... the result is a rustfree knife with a razor edge. Hard to sharpen, but the blade stays sharp through an entire deer-skinning process. The blade shape is what is known as a drop-point skinner, and is about 4" long. I don't like long, pointy knives. The F1 is expensive, probably around $125 or so these days. The Swedish Air Force uses it as its pilot survival knife, similar to the way our AF uses the KaBar. The handle is a little thin if you have big hands, as it is made to be used with gloves or mittens on. Mine has a custom handle, but they no longer sell the blank I used to make mine, so you're kind of stuck with the manufactured ones now.
The Condor Nessmuk was slightly modified by its previous owner and shortened just a tad. It started life as a dedicated skinning knife, made popular by mr nessmuk. I like the heavier blade for cutting off squirrel and rabbit limbs, and the wider blade bump provides a good grip when gutting large game (I know, not a requirement. But this part of my post is about what I use and why.) The steel is 1075 or 1095, i can't remember (but it's listed on their web site) and not too hard to maintain. Sharpens well, but not as durable as the VG10. I forget what they cost, but it's not expensive... probably $35 to $50, maybe as high as $75... not sure, as it was a gift.
The third knife is one that I use when I fly up to NY. I got tired of explaining knives in my checked baggage to the wonderful TSA employees, so I bought something to just leave up there with my folks. It's a very old (1960s) Western L66... this is a clip point (pointy) skinner, but since I don't hunt in NY, it's a great fish cleaner and cooking knife around the campfire. I don't know what kind of steel it is (something carbon and REALLY easy to sharpen) but it rusts quickly around canoes... That's the nature of carbon steel... keep it oiled and out of the rain and it's fine. It cost me $26 plus shipping on eBay a few years ago.
So, all that said, I'd refer you to a Condor knife, drop point design, 4.5"-5" long, or a Mora Robust.