The Ontario Mark 3 Navy (MKIII) is the standard
knife
A knife (: knives; from Old Norse 'knife, dirk') is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least Stone Age, 2.5 million years ago, as e ...
for the
US Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
and
Navy SEAL
The United States Navy Sea, Air, and Land (SEAL) Teams, commonly known as Navy SEALs, are the United States Navy's primary special operations force and a component of the United States Naval Special Warfare Command. Among the SEALs' main funct ...
s.
History
The Mark 3 was officially adopted by some units in the United States around 1970, and was also sold for general sale.
It wasn't till late 1982, that it was officially adopted as the "standard issue fighting/utility knife" for the Navy Seals.
It also was once and may still be, used by Reconnaissance Marines at the Combatant Divers Course in Panama City, Florida.
Design
The Mark 3 features a 440
stainless steel
Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...
blade.
The Mark 3 has a saw tooth back and a
black oxide
Black oxide or blackening is a conversion coating for ferrous materials, stainless steel, copper and copper based alloys, zinc, powdered metals, and silver solder. It is used to add mild corrosion resistance, for appearance, and to minimize light ...
finish, with high impact plastic handle and sheath.
The original Mark 3 had a steep counter curved point which the Navy requested be reinforced because of damage to the tip of the blade when prying. They have since reinforced the tip eliminating the reverse curve making the point more sturdy.
People have found many uses for this knife, many of which are mentioned in marketing, including using the butt as a
hammer
A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...
, using the back serrated saw edge to cut, and using the thick blade as a
prybar. The blade is said to hold a great edge and be very durable.
Usage
As of 2025, It isn't clear if the knife was ever replaced, or instead Navy Seals are allowed to pick their own knives.
Users
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Hong Kong Police Force
The Hong Kong Police Force (HKPF) is the primary law enforcement, investigative agency, and largest Hong Kong Disciplined Services, disciplined service under the Security Bureau (Hong Kong), Security Bureau of Hong Kong.
Pursuant to the one c ...
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See also
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M9 bayonet
The M9 bayonet, officially known as the M9 Phrobis III, is an American multi-purpose knife and bayonet officially adopted in 1986 by the United States Armed Forces for the M16 rifle.
History
In 1973, the U.S. military retired the M7 bayonet, i ...
*
Strider SMF
The Strider SMF is a framelock folding knife that was specifically developed for Det One, the first unit of the United States Marine Corps (USMC) under the United States Special Operations Command (SOCOM). The Strider SMF was the first knife iss ...
*
SARK
Sark (Sercquiais: or , ) is an island in the southwestern English Channel, off the coast of Normandy, and part of the archipelago of the Channel Islands. It is a self-governing British Crown Dependencies, Crown Dependency, with its own set o ...
*
CQC-6
The CQC-6 (Close Quarters Combat — Six) or Viper Six is a handmade tactical folding knife with a tantō blade manufactured by knifemaker Ernest Emerson and is credited as the knife that popularized the concept of the tactical folding knif ...
*
Commander (knife)
The Commander (knife) is a large recurve folding knife made by Emerson Knives, Inc. that was based on a custom design, the ES1-M, by Ernest Emerson that he originally built for a West Coast Navy SEAL Team.
History
Ernest Emerson was working on ...
*
Aircrew Survival Egress Knife
The Aircrew Survival Egress Knife or ASEK is a United States Army, U.S. Army aircrew survival knife, designed and initially manufactured by the Ontario Knife Company, and entered service in 2003.
Features
The ASEK has a number of features set ...
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OKC-3S Bayonet
The OKC-3S is a bayonet developed for the United States Marine Corps.
History
The OKC-3S is part of a series of weapon improvements begun in 2001 by Commandant of the Marine Corps James L. Jones to expand and toughen hand-to-hand combat trainin ...
*
KA-BAR
References
{{Reflist
Military knives
Equipment of the United States Navy