The Ontario Mark III Navy Knife features a 440A stainless steel blade with a black oxide finish and a molded high impact plastic handle. Overall, the Mark III Navy Knife is 10.75" long, consisting of a 6.5" blade that is .65" thick. The Mark III Navy Knife sheath is also a molded high impact plastic that is equipped with a brass belt loop and hanger.
The Ontario Mark III Navy Knife is used exclusively by the United States Navy.
Limited Lifetime Warranty
Posted by Michael on 7th Nov 2015
I'm quite surprised that this knife is issued to U.S. Navy Seals. I suspect their reaction to it must be similar to my own. The grip is far too short. Therefore, the knife feels very uncomfortable and very unwieldy in my hand, despite the rough stippling. Please note: I am not a big guy. And the average commando must have bigger hands than mine. This knife would have to be completely unsat for them, especially if they were to use it for hard underwater work, and most especially if they had to use it for combat. I personally don't even want to use it for a letter opener. I expect the Ontario company offered the navy the lowest bid to make the product. And was able to make it so cheaply by dropping an inch-and-a-half off the handle.
Posted by Thomas on 14th Sep 2013
I have spent years collecting all kinds of knives from pocket size to survival to combat and this knife does not disappoint. Nice weight, sharp blade. You can't shave with it but it will certainly do the job. I give it 5 stars. I would recommend this knife to anybody.
Posted by Harry UDT on 18th Apr 2013
When a knife is hard to sharpen, that means it is made of hard steel and will hold that edge. Just keep working on it.
Posted by Unknown on 13th Oct 2012
Very obviously this knife is designed with one purpose in mind. That being said, if you want a knife with heavy weight, like this one, that can also chop wood and then be re-edged, then try a Busse. Hold on to your pants though, as a Busse will set you back a few hundred bucks. They were originally designed for Spec Ops operators, and can take some punishment.
The MK III, out of the box, has a slightly rolled edge on it, meaning that it is not "straight." A few strokes on a steel with re-straighten the edged and knock off any burrs as well.
Granted, it is a little difficult to sharpen if you want to preserve the black oxide finish, but it is High Carbon Tool Steel, and thus, is relatively easy to put an edge on it. Remember, this knife had one intended purpose, so you will never get it to the point that you could shave with it.
It takes a little more time than making some passes on a wet-stone to sharpen, especially since you don't want to scratch the oxide finish, but it can be done.
I use 3M sanding sponges, which come in a variety of grit...even up to microfine grit (for polishing the edge), a little patience and care, and finish up on a strop (I made my own stroping block out of a strip of 8 ounce leather, and a 12" piece of 2x4. Simply stretch the leather lengthwise down the 2x4, and screw, or nail the leather at each crosscut - simple process). Load up the leather with some polishing compound (I prefer the green for polish it leaves...I can't remember the grit value of the green, so you'll have to research that one), and strop both sides of the blade an equal amount until you have the edge to where you want it.
So overall, a little cumbersome, but it can be done. And yes, they do look stellar in the movies.
Posted by Justin Case on 26th Jul 2011
Forget sharpening it to a fine edge, it's not a knife for that. This knife is made for puncturing and causing damage, right?
it's a (real...) military knife serving a fairly different purpose than most people would use them for.
Love mine, got it as a factory second.
Posted by Barsby on 4th May 2011
I have owned my Ontario MK-3 for about 15 years. I love most of the Ontario knives, with the exception of the MK-3 Navy Knife. It's grind has a very poor angle, which makes it IMPOSSIBLE to put a sharp edge on it. I have been trying various products over the years, such as Arkansas stones and Diamond stones, but nothing works. It doesn't even make a good butter knife. BUT, it does look very cool in the movies. :)