It’s not difficult to equate diving with adventure. Seasoned divers and hobbyists aren’t inured to the majesty of the sea and its floor of aquatic life. It’s easy to get caught up in all that hype and forget a vital piece of equipment. Dive knives have been regular companions to divers for decades, and with good reason.
Popular adventure films have mythologized the dive knife to a level that’s far removed from reality. This tool isn’t intended to be used as a weapon beneath the water. Generally speaking, a dive knife is a critical tool that serves the purpose of safety more than anything else. During a dive, divers who are caught in a tangle of kelp, a fishing line, or other material can use the knife to cut free.
A dive knife has other uses as well. Divers who are into spearfishing or kelp fishing cannot dive without a knife. Spearfishing is the ancient practice of catching fish in rivers and streams using sticks that have been sharpened to a fine point. The modern dive knife originated from these makeshift tools.
Divers who spearfish use the knife to deliver a kill spike to the fishes they catch. The Japanese call this practice ikejime or ikijime, Traditionally, Japanese fishermen drive their knives directly into the hindbrain of a fish. Ikijime kills the fish nearly instantaneously. The Japanese believe that killing a fish as quickly as possible improves its flavor. Ikijime prevents adrenaline buildup and ensures that the catch is as fresh as possible.
Divers who are interested in kelp fishing also require the use of a dive knife. Kelp beds are a great spot for catching small sea life. In this environment, dive knives are used to shear off the thick kelp plants that may entangle the diver.
Knowing the uses of a dive knife is all well and good, but how do you find the perfect knife? Before you purchase a knife, it’s vital for your to have a good grip on the nature of your needs as a diver. No one knife is the best knife. Depending on your intention, you might be better off picking a specific option over all the others. Prevent yourself from picking the cheapest knife available. In this case, cheaper isn’t always better.
Dive Knife Details
Choosing a dive knife is an art in itself. Ideally, the perfect diving knife should sport a hard edge, is resistant to breaking, and resistant to the corrosive effects of saltwater. Ultimately, there isn’t a knife that can do it all. Again, depending on your dive, one knife will work best over the other.
The first detail that a diver has to home in on is the material of the knife itself. Dive knives are either made out of titanium or steel. Knowing the difference between both will affect your decision drastically.
A titanium knife
- Is the best when it comes to resisting the corrosive effects of the ocean.
- Is Incredibly strong.
- Virtually needs no maintenance.
- Con: This is the most difficult knife material to sharpen.
A steel knife
- Is easy to sharpen.
- Comes in 2 alloy grades: 300 and 400.
- Con: A 300 alloy knife comes close to mimicking the corrosion resistance of a titanium knife but is also more difficult to sharpen than its 400 grade counterpart.
- Con: A 300 grade alloy knife tends to lose its edge faster than its 400 grade counterpart.
- Con: A 400 grade alloy knife requires a lot of maintenance.
- Takeaway: Purchasing a steel knife will require you to deal with one out of two possible scenarios. A 300 grade alloy knife requires intensive sharpening procedures while a 400 grade alloy knife will require you to carry out more thorough cleaning methods.
Maintaining a Steel Knife
There is a method to maintaining a steel knife properly. Follow these steps immediately after your dive:
- If your knife features a detachable handle, take it off.
- Rinse the knife with fresh water. Include the knife’s sheath during the rinse.
- After rinsing, use a soft piece of cloth to dry the knife and its sheath.
- Dry the knife in a well lit area so you can easily spot possible signs of corrosion and other stains.
- Once your knife is dry, leave it exposed.
- Use a silicone based lubricant (avoid anything that’s petroleum based) and apply a light coat of polish on the knife.
- Sheath your knife once you’re done.
Dive knives are either small or large. How do you know which size knife is ideal for you? If you’re a recreational diver, choosing a smaller sized dive knife would be the practical choice for you to make. Bigger knives only become necessary when you’re a diver who’s going on more specialized dives.
Small Dive Knives
- Typically measure in at 3 – 4 inches.
- Are best for recreational divers who intend to use the knife sparingly.
- Used to cut free of anything that might entangle the diver.
Big Dive Knives
- Measure in at 5 inches and up.
- Are ideal for serious dives like kelp fishing, spearfishing, etc.
- Bigger knives give a more comfortable grip. This especially becomes apparent during long dives.
- These knives are best for cutting fishing moorings, lobster trap lines, and any material that might obstruct your diving ship’s inboard engine.
- Caveat: Knives that exceed 5 inches will compromise your aquatic mobility.
Size: How do you plan to use it? are you a recreational diver or are you going on intensive diving expeditions?
Dimensions and Design
An excellent dive knife sports a blade and grip that are equal in length. Again, your needs as a diver come into play when questions involving knife design surface. Choose a big knife if you’re going to be engaged in a lot of hacking, sawing, and prying activity underwater. If you’re using the knife as a precautionary measure, choose something that’s more compact.
Choosing a knife will require you to select either a fixed blade or a foldable blade. This decision depends on the diver’s preferences more than anything else.
A Fixed Blade
- Comes with a sheath.
- Will require the diver to unsheathe the knife with one hand.
- Not ideal for divers who struggle with constant situational awareness. Leaving the knife unsheathed during a dive could cause accidental cuts and injuries.
A Foldable Blade
- Locks in an open position. This mechanism prevents the possibility of an accidental cut during a dive.
- Is the ideal choice for minimizing injuries during a dive.
- Is smaller and lighter than the fixed blade variation.
- Requires the diver to use both hands to release it from the locked position. Difficult to open with one hand.
A dive knife’s shape will be apparent from the way its edge and tip is formed. Depending on what you’re looking at, a dive knife’s edge can be either straight or serrated. Serrated edges are best at cutting kelp and natural fibers like ropes. Straight edged blades easily cut through nylon material, plastic, and fishing lines.
Fortunately, you don’t have to compromise when it comes to shape. The best knife combines a serrated and straight edge. Just make sure that you find a knife that’s long enough to allow you to use both edges comfortably.
There are three options available when it comes to a dive knife’s tip. Knife tips are either blunt, sharp, or tanto. The question of safety remains at the forefront when you begin weighing the three tip variations.
If you’re a recreational diver, it would be best to use a knife with a blunt tip. This is the safest knife tip available and the chances of you cutting yourself while you use it is slim. Blunt tips are best for hacking, digging, and prying material off surfaces.
Professional divers who know their way around the uses of a dive knife might prefer using a sharp tip. While using this does increase the chances of accidents, there’s nothing like a sharp tip when it comes to executing cutting and puncturing movements. If you’re going spearfishing, this is the knife tip that you want.
Knives that feature a tanto tip offer a delicate balance that synthesizes the sharp and blunt variations. Divers who are looking for a compromise will appreciate this hybrid. Tanto tips have an angled tip that’s sharpened for cutting. The very tip of the knife is blunt.
There are two schools of thought when it comes to knife placement. Traditionally, knives used to be strapped on the leg opposite the diver’s dominant hand. A disadvantage of this method is that the knife can become easily entangled during a dive.
Modern divers who bring a slew of equipment typically place their knives in a buoyancy compensator for easy retrieval and storage. This method is more efficient than what traditional divers are used to but it does require the use of more equipment.
Now that you have a good grip on the essential features that a dive knife has to have, There are a few other details that need to be examined. While these aren’t critical features to have, knives that have these seemingly minor features are a step up from options that don’t.
Knives that have a metal butt can be used as a hammer provided that its size is big enough. A metal butt or pommel is an excellent tool for banging on metal surfaces to create noise that can serve as a signal during a dive.
Line Cutting Notch
A line cutting notch helps you to immediately cut loose of anything that might entangle you. Use the line cutting notch to hook the line that’s obstructing your dive and cut yourself free immediately.
This is a detail that some divers overlook. Check the handle of the knife to see if it features well designed finger grips. This difference drastically affects how comfortable gripping the knife is during your dive.
Black blades can be covetable for divers because of one reason: they tend to be less reflective underwater. Having a less reflective blade in tow reduces your chances of disturbing or attracting marine life. Still, this feature is both boon and bane. Losing your grip on this blade during a dive can result in a lost knife. Black blades are difficult to spot in deep waters.
Reviewing Dive Knife Options
Determining the nature of your needs as a diver and absorbing all of the details that go into the making of a good dive knife are critical when you want to purchase the perfect option. To make your task a little easier, we’ve come up with solid selection of dive knives. Whether you’re a hobbyist or a diver that’s on the lookout for something that has a sharper edge, you’re sure to find the best companion on your dives in this roundup of dive knife reviews.
Aqua Lung Argonaut Titanium Diving Knife
The Aqua Lung Argonaut was designed by its manufacturer to be their most robust offering. In terms of size, the Argonaut measures in at 9.75 inches. This is one of the larger knives available in our selection. Its size does justice to its capabilities. Fashioned out of sleek black titanium, the Argonaut is virtually immune to rusting.
Depending on your preferences, you get to purchase the argonaut in a spartan (sharp) or blunt tip. The knife’s handle features a parachute cord that you can fiddle with and rewrap in a design of your own making. The Argonaut’s edge sports smooth and serrated sections so you won’t have to make a hard choice in that department. Cutting through kelp, fishing lines, and other material won’t be a chore when you bring this knife along. In terms of aesthetics and functionality, this is a beautiful piece of equipment that serves its owner well during the most demanding dives.
Atomic Aquatics Titanium Ti6 Scuba Diving Knife
Atomic Aquatics’ Titanium Ti6 diving knife is another full sized knife that packs a punch. Its lightweight profile makes it an attractive option for different classes of divers. What’s really fantastic about this option is that it’s beautifully balanced. Using this knife during a dive won’t feel unnatural. The finger grips on the Ti6’s handle provides a comfortable grip and its titanium material eliminates corrosion concerns.
Depending on your tastes, you can opt for either a blunt or sharp tip with the Ti6. Cutting through obstruction is a pretty straightforward affair with this knife but prying is another story. Avoid using this knife for anything that may involve heavy prying activity. Apart from that detail, the Ti6’s smooth and serrated edge, curved design, lightweight profile, line cutting notch, and corrosive resistance makes it a premium pick for divers everywhere.
Cressi Skorpion Dive Knife
The Cressi Skorpion is a medium sized knife that comes in at 4 3/8 inches. Cressi has been making scuba gear since 1946 and the Scorpion is a satisfying summation of all that experience. Users could opt for either a sharp or blunt tipped Skorpion knife. The knife features a straight edge on one side and serrations on the other. A line cutting notch on the serrated side makes short work of tangled lines.
A downside to this knife is that it doesn’t come in titanium. Users who are interested in purchasing the Scorpion need to make a choice between a 420 grade Japanese stainless steel alloy for extra sharpness or a 304 grade stainless steel alloy for higher corrosion resistance. Divers who are looking for something that they can bring during spearfishing expeditions will want to purchase the 420 grade alloy option. In spite of this hiccup, the Skorpion’s inclusion of serrated and straight edges, its line cutting notch, and sheer affordability makes it a popular option.
Cressi Borg, Long Blade Knife
The Cressi Borg’s 5 1/2 inch edge was designed with spearfishing in mind. This long blade option was made for a quick aquatic capture through the use of its sharp tip, stainless steel blade, and straight and serrated edges. Instead of going sharp, casual drivers have the option of going for a blunt tip.
Unlike the Skorpion, you won’t have the luxury of choosing a 420 grade Japanese stainless steel alloy. Users of the Borg will have to contend with its 304 grade alloy stainless steel. This makes it resistant to corrosion but you’ll still have to sharpen it to keep its edge. Size is also a factor. Some divers will find its 10.5 inch size to be too cumbersome for a regular dive. On the flip side, its size and hammer pommel makes it a great knife to use for anything that involves heavy prying and hammering. Spearfishing enthusiasts will want this knife while other divers may want to look for a more modestly sized offering.
Promate Scuba Dive Snorkel Titanium Knife
As far as dive knives are concerned, the Promate Scuba Dive Snorkel Titanium knife’s one of the more popular options. It’s easy to see why when you factor in the Promate’s titanium material, comfortable rubber grip, straight and serrated edge, and forgiving price tag. The Promate comes in either a sharp or blunt tip and features a line cutting notch. A hammer nub located at the base of the handle is excellent for divers who rely on creating noise for underwater signals.
The Promate comes with a sheath that you can attach to your leg during a dive. Still, be warned. The material of the Promate’s sheath isn’t the best when it comes to securing the knife in place. Divers who strap this knife on their leg may find that it slips away mid-swim. If you have a buoyancy compressor, this won’t be a problem. Negatives aside, the Promate’s medium sized blade, excellent grip, and decent price make it a safe choice for most divers.
Underwater Kinetics – Blue Tang Titanium Dive Knife
Underwater Kinetics’ Blue Tang Titanium dive knife is an affordable option that’s easy to take apart. You won’t need tools to remove the Blue Tang’s pommel and its 5 inch titanium edge won’t corrode. Like a lot of dive knives, the Blue Tang Titanium has a straight edge, a serrated edge, and a line cutting notch.
In terms of cutting ability, the Blue Tang Titanium does a good job of cutting through a variety of obstructions. Still, most of the other knife options on this list tend to outperform the Blue Tang in that department. The knife’s sheath comes with a quick release button which you’re going to rely on a lot given the fact that its difficult to unsheathe this knife while both hands are fully gloved. What’s great about this titanium knife is that it doesn’t come with a steep cost. If you’re into spearfishing, make sure to purchase a variation that comes with a sharp tip instead of one that’s blunt.
If you’ve read this far, you already have enough knowledge to make the act of selecting a dive knife an exercise in simplicity. Start with your intention as a diver. After you’ve determined that, pay close attention to the constellation of details that make a great dive knife. Know that a knife’s material, size, dimensions, blade variations, and shape are the details that take precedence over anything else.
While the best dive knives will come with a price, you don’t have to be stuck with subpar options if you’re on a budget. You can still find a decent knife that won’t give your wallet a beating if you do your research well. Know that after you’ve purchased your knife, you’ll have to adhere to a faithful maintenance procedure if you want to keep it in rotation for years. Keep your needs as a diver paramount and scrutinize every detail available to maximize the investment that you make on a dive knife.