Diving knives – faithful underwater companions

The need for the cutting edge 

Since the beginning of human exploration of the deep, solid diving knives have been an essential piece of equipment  The wet suits and the aqualung have long ago replaced the heavy brass helmets and lead shoes of the “three-bolt set”. In the advent of snorkeling, the diving equipment comes in all shapes and colors, but the role of diving knives as staple tools has remained.

Yes, tools. As you can run without proper training shoes, you can dive without a good diving knife, but its objectively easier to do it with a piece of proper equipment. From its early days, diving knives have been designed as a tool, not a weapon. Fending off sea abominations with a knife is no wiser that engaging a full sized grizzly in the Alaskan wilderness with a dropoint. The tasks which a diving knife should preform are various and diverse. Under the water, it includes cutting all sorts of synthetic lines, netting, ropes, separating clams and limpets from the rocky bottom. Sometimes it can even serve as a leverage, helping to release a jammed anchor, or a hammer for breaking off pieces of rock. In the boat, you may have to cut a fishing line, for example to release a poisonous fish such is the weever, chop a bait or stun a freshly caught fish. From time to time, you will have to cut trough a piece of hemp or nylon string entangling the propeller. On the shore, a diving knife comes handy for breaking shells, opening up scallops, dressing the fish, or chopping wood for the grill.

However, the most important task of a good diving knife is to save your life. No shark is dangerous as an innocent looking piece of fishing net, which is hard to see, and even harder to break through. To make the matter worse, they are easy to come by at the most attractive diving sites, as the fishermen also seek the locations brimming with sea life. Besides the anchored nets, even more dangerous are the torn pieces which are drifting around with the current. Without a knife, the net becomes a deadly trap. Any knife might set you free, but with a sturdy and well designed diving knife, your chances to survive get a lot better.

The origins of a diving knife – Spirodag

The champion among the old school diving knives was the Spirodag, made by French based “La Spirotehnique”. It was sought by professionals and amateur divers alike. It’s two-edged, blade was so wide that it quickly earned its nickname – spare oar. Its blade, which was fully serrated on one edge  ended with a flat tip which could serve as an emergency screwdriver. With its large comfortable handle and wide plastic sheath, the knife was no beauty. However, the lack of elegance was compensated with great efficiency and unexpectedly wide range of application, under of above the water. Many serious divers still choose proven, heavy designs over the modern, ultralight titanium blades.

Not so much a diving knife – The Fallkniven A-1

The Fallkniven A-1 wasn’t originally designed as a diving knife, although many retailers still advertize it as one. It’s features were, on the other hand, promising. The knife handle molded from thermorun polymer wraps a respectable 6 mm thick and 160 mm long VG-10 blade. The full tang construction of the blade is protruding at the end of the handle, like a hammer. The knife weighs only 300 g and comes in a sturdy zytel sheath.

Unfortunately, the proverbial Swedish quality has failed at this one. The edge is so soft that it can be folded sideways with a fingernail. Any serious use calls for immediate sharpening. The handle is comfortable, and well shaped, but it’s not designed for underwater use in gloves. Towards the blade, the handle flares into a handguard, which could have been larger. The blade is thick, convex ground, and strong enough to provide leverage if needed. Lack of serrations might prove cutting through netting and ropes bit of a challenge. The sheath, although made of glass reinforced polymer is nothing to write home about, especially because of cheap securing solution. For its price of around 200 euros, it fits in the competition, but as a diving knife, it’s not worth half of its price. It’s definitely a “land knife”.

German killer whale – Boker Orca II

Boker Orca II is a second, modified version of the knife adopted by German elite GSG-9 and KSK units. Orca II boasts a 135 mm razor edge  recurved blade made of special X-15 T.M. steel. The blade has a false edge which makes stabbing with a 6.5 mm blade much easier. Deep concave grind might not be the best solution, especially for carving tasks, however, it enables for thin profile just above the bevel  which excels in cutting ropes. The long “S” shaped blade would probably be outstanding in cutting through fishing nets, but it has always been a challenge to resharpen. The handle is large enough, made of hytrel. It gives a good grip and excellent control in all positions, even with gloves on. The cordura sheath has a plastic inlay, which can be flipped for a left-handed user. It’s been designed to hang from the belt, but it also has straps for fastening it around leg, as well as attaching to the BCD.

Toys for seals – SOG champions

SOG Seal Team 2000

Created according to the requirements of famous Navy Seals, the SOG Seal Team 2000 has been advertized as the most thoroughly tested knife ever. The tests included resistance to bending, torsion, tip breaking, corrosion after two weeks in salty water, heating with a blowtorch, rope cutting tests, edge retention tests, stabbing tests, handling tests… Truth be told, the Seal Team is an excellent choice for both sea and land.

SOG Bowie

The 178 mm long and 6.1 mm thick blade is shaped similar to the legendary SOG Bowie from the Vietnam era, and is partially serrated in the first third of the lower side. The steel is Japanese AUS-8 and is coated with dark-gray protective layer. The fairly big handle is made of glass-reinforced nylon and features an asymmetrical handguard and exposed end of the tang, which can be used as a hammer. The knife weighs 292 g, and comes with an excellent kydex sheath. It can be easily attached on almost every part of equipment and holds the knife securely, even without the safety rubber band. The sheath is tactical, which means that it makes no sound, which is essential for the special forces. The flat ground blade is an excellent choice for an universal field knife. The tip is very tough and yet thin enough for delicate work. Truly universal field knife with wide range of use, the Seal Team 2000 is more than worth its price of 160 USD.

SOG Demo

SOG Demo is a modified version of Oplan 34 Alpha knife, which was designed for Special Operations groups during the Vietnam War. It’s similar to Randall Mod.16 diving knife, with its spear point tip, fully serrated spine, and the flat ground fuller. Its 183 mm AUS-8 blade is 5.8 mm thick. It comes razor sharp straight from the factory and is protected with black TiNi coat. The comfortable handle is made of soft Kraton with simple lines and shallow indents for fingers. The two white lines across the handle have purely aesthetic purpose. The bottom of the handle features a massive piece of steel screwed in, which can be used as a hammer, but also gives this knife great balance.

The fully serrated upper edge is an unmatched solution for cutting ropes and nets, which can mean the difference between a life or death for a diver. The blade is cryo-treated, which gives it outstanding edge retention, and the tests have shown a total rust resistance. The only serious drawback is the leather sheath. It is made of black leather with a pocket holding a medium-grit Norton sharpening stone. It seems that the sheath designers have missed the underwater aspect of this exceptional knife, which should by all rights come with a kydex or at least quality nylon sheath.