Mark 3 Knife

The Ontario Mark 3 Navy (MKIII) is the standard knife for the US Navy and Navy SEALs. It also was once and may still be, used by Reconnaissance Marines at the Combatant Divers Course in Panama City, Florida.

History and Durability

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. As of 2025, It isn't clear if the knife was ever replaced, or instead Navy Seals are allowed to pick their own knives.

It features a 6.0 in (15 cm) 440 stainless steel blade. It has a saw tooth back and a black oxide finish, with high impact plastic handle and sheath. The original 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, 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

Apart from the USA, Mark 3 knife is issued to officers of Special Duties Unit and Counter Terrorism Response Unit of the Hong Kong Police Force.

Users

• Hong Kong
• United States