While it certainly sounds cool, dive knives are not for fending off waves of sharks in the ocean.
Dive knives are for safety. There are several horror stories of divers becoming entangled in kelp or fishing line, and succumbing to the ocean. If these divers remained calm and came prepared with a cutting device, they may be here today to tell the tale.
So that leads us to the question.
Do I need a scuba diving knife?
The short answer to that question is no you don’t. They are recommended pieces of diving safety equipment that frequent divers should have. Cutting debris from coral or getting yourself lost from entanglement by having a knife or shears makes the dive safer for all those involved including yourself.
Which type of cutting implement should I get for diving?
We’ve tested all of the main diving knife options including line cutters, and dive shears, and compiled a list of the best five options, and what they are best for, allowing you to make a purchase you are happy with.
Let’s dive in.
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Budget Option
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Luxury Option
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Best Line Cutter
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Best Shears
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$34.95
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$150.99
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$29.95
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$32.00
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- Budget Friendly
- Has serrated and smooth edge + line cutter
- Stainless steel will rust
- Sharp tip can be less safe
Our best all-around selection is the Cressi Skorpion diving knife. The blade features serrated and smooth edges, as well as line-cutting elements, ensuring its versatility.
Both sides of the blade are easy to sharpen and its special coating helps the stainless steel resist corrosion from saltwater.
This lightweight diving knife comes with a snugly fitting sheath, which has a locking mechanism that you can release with one hand.
The handle is molded rubber with a tank-banging tip and is a suitable size for both men and women. Two long rubber straps mean it can be attached to the arm or leg.
- Blade Length: 4 ¾ inch blade
- Blade Type: Serrated, Sharp, Line Cutter
- Material: Stainless-steel
- Tip: Sharp
- Attachment Style: Strap
- Price: Low
- Somewhat blunted tip
- Incredibly durable titanium
- Will not rust
- Serrated, smooth, and line cutter edges
- Not budget friendly
The ScubaPro Mako is a small, lightweight titanium knife, perfect for diving and traveling. Its blade is quite small but is completely fit for purpose, with a wickedly sharp, corrosion-resistant titanium blade. Titanium ensures it is extremely resistant to rust as well as incredibly strong and light.
It features both smooth and serrated edges with a line-cutting notch. the Mako has a sharp tip but is still somewhat blunted tip for the versatility of use.
It is a very compact model and a thin handle means it sits in a very low profile against the leg or BCD strap.
Its sheath has a secure push-button lock mechanism for safety and easily adjustable straps.
The handle is suitable for both left and right-handed people and the tip of the handle has a dual purpose as a metal tank banger and a bottle opener.
The ScubaPro Mako is a popular and reliable diving knife in the scuba community. The only downside is the slightly more expensive cost, but you can be sure you are getting reliability for your buck.
- Blade Length: 3.5 inch blade
- Blade Type: Serrated, Sharp, Line Cutter
- Material: Stainless-steel
- Tip: Blunted Sharp Edge
- Attachment Style: Strap
- Price: Med-high
If you don’t already own a cutting tool for scuba diving, the EEZYCUT Trilobite is a great place to start.
It’s very affordable and can slice through the toughest of lines you’ll encounter when scuba diving.
Whilst its backward-facing, stainless steel blade poses no danger to fingers or hoses, it is designed to slice easily through the fishing lines, nets, and scuba webbing and can even cut through a drysuit if required.
It can’t cut anything thicker than 0.47 inches in thickness though, and it won’t be much use in difficult environments like kelp forests if you are diving in those.
- Blade Length: N/A
- Blade Type: Sharp but guarded
- Material: Stainless-steel
- Tip: N/A
- Attachment Style: Strap or Pocket
- Price: Low
You can get many different types of diving shears, some of which function as both knives and shears, the most effective and best scuba diving shears are actually simple Trauma Shears used by emergency responders around the world.
This strong, scissor-like tool will cut through nearly anything and comes in conveniently sized nylon pouches. The loops and straps mean they can be threaded onto a waistband or strap, looped through rings, or stored in a pocket.
Caring for these shears is especially important as it is easy for saltwater to get stuck in the mechanism and cause rust and corrosion.
Smooth movement is the key to shears, so be sure to rinse and dry them thoroughly after each use and consider using protective oil. Even so, expect to have to replace these more often than dive knives.
- Blade Length: N/A
- Blade Type: Sharp but guarded
- Material: Stainless-steel
- Tip: N/A
- Attachment Style: Strap
- Price: Low-Mid
What are Dive Knives and Shears?
Scuba diving knives and shears are designed to be able to cut through anything which might entangle you underwater. This can include nets, fishing lines, or even your own equipment.
You might be wondering how a dive knife is different from the kind in your kitchen drawer. Well first off, safety is a major issue – you don’t want sharp pointy objects anywhere near the air hoses that are keeping you alive.
Many dive knives have slightly blunted tips for this reason, though the blades are incredibly sharp and very sturdy. Another essential aspect is the resistance to salt corrosion, which would quickly destroy your average kitchen blade!
Let’s have a look at a few different types on offer:
Knives
Does what it says on the tin. These knives often have both smooth edges and serrated edges so they can be used in multiple ways.
It usually comes with a fitted sheath that can be strapped to the arm, leg or BCD.
Shears
Shears are more like scissors than a knife, though the blade is much sharper than your average pair of scissors and the mechanism is much more powerful to allow the cutting of straps, a thick netting, and even dry suits.
Line Cutters
These tools are the most safety-conscious, as the blade is protected and it’s difficult to accidentally cut yourself or your life-saving air hoses. They’re also great for travel, as they are allowed into countries were carrying knives is prohibited.
Why are They Important?
When divers think about emergencies, they usually think about things like out-of-gas situations or getting stung by wildlife, but many overlook the silent killer of the scuba world:
Entanglement
Entanglements can be deadly because you’re relying on the gas you have left in your tank, and your (hopefully very close by) buddy to keep you alive. A bad entanglement can result in an out-of-air scenario.
This scenario works both ways, if your buddy finds himself entangled in a ghost net, you’re going to wish you’d bought that knife.
You can also use knives to have a positive environmental impact. Encountering a turtle with a net around its neck is incredibly sad and it’ll be even more heartbreaking if you don’t have a diving knife handy to help free it. They can also be used to safely remove lines and nets from reefs without disrupting the coral.
A good scuba diver must be a jack of all trades, and a good scuba diving knife allows him to be helpful in many different scenarios. In addition, some countries require divers to carry a knife as a safety precaution.
Do I Need One?
We all hope we’ll never have to use a dive knife. It’s undeniable that a good, reliable scuba diving knife or pair of diving shears is worth every penny spent.
You never know when you’ll encounter a scuba diving emergency, but having a great diving knife will mean you’re as prepared as possible.
It’ll also provide peace of mind for yourself and your dive buddy. This makes dive knives a basic safety choice. Carry more than one, and different types.
If you’re a beginner diver, this probably isn’t the first piece of equipment you should buy. A well-fitting scuba mask or a vital dive computer should be your first stop.
When you’re diving with an instructor or divemaster, feel free to check that they’re carrying a dive knife or shears, to put your mind at ease. If you are diving frequently, a diving knife is essential. If you are leading your own dives with a buddy, or even by yourself, you should be carrying at least one back up too.
Things to Look For in a Dive Knife
Tip
Extremely sharp tips are favored by fishermen and more experienced divers. They can be useful but can cause injuries and damage to equipment in inexperienced hands.
Blunt tips are good for beginners and are more useful as they can be used for digging or prying. They are safer to handle around hoses too.
Size
Bigger isn’t always better with a diving knife. Most dive knives range from 3 to 6 inches though many find smaller knives optimal as they are easier to carry and store without added bulk as well as being easier to control underwater.
Considering we aren’t using this dive knife to defend ourselves from sharks or angry divers, we just need something that can cut fishing lines, kelp, and potentially scuba gear in the event of an emergency.
Blade
There are two types of blade edges, serrated and smooth. In the picture above, both sides have one of them. The top side is serrated, whereas the bottom side is smooth. The ideal dive knife should have both for versatility.
The straighter edge is useful for cutting plastics and lines whilst the serrated is suited to sawing through natural-based materials like rope and kelp fronds. If you have to choose, the serrated edge is more useful.
Other useful additions to the blade include line-cutting notches which can slice through lines with little to no effort.
Material
Your average kitchen knife will quickly rust and corrode when exposed to the harsh ocean environment. The best material for your dive knife blade is either titanium or stainless steel.
Stainless steel will require regular sharpening and maintenance with oil to prevent corrosion from contact with salt water. Even if dive knives advertise a coating for stainless steel, it can still be scratched leaving it vulnerable to seawater.
Titanium blades are lighter, stronger, and require less maintenance and sharpening, but they are more expensive and harder to sharpen.
Handle
Metal handles are convenient for banging on your tank to get your buddy’s attention but are slippery and difficult to hold.
A well-designed ergonomic comfortable handle will make you much less likely to slip or drop it. Some also have added features like tank bangers or can be used as a hammer-like tools.
Color
Thinking about the color of a diving knife might seem a little superficial but it’s an important consideration.
Whilst slick, black models look smart and are ideal for hunters (they blend in more), bright colors ensure that your knife can be seen when it’s most needed.
This could be when your buddy needs to grab it quickly, or when you’ve just dropped it on the seabed.
Attachments
This is the way you will attach your dive knife or shears to your gear. There are several options:
- BCD/Hose Mounted – A secure way to attach it to your gear, easy to access and not easily forgotten. Remember to clean and dry regularly, though.
- Leg Mounted – These knives come with straps to attach to your calf or thigh. It has the benefit of quick access but it can get caught on things or fall out if it isn’t secure in the sheath.
- Foldable knives – These can be stored in the BCD pocket, making them a great, safety-conscious choice. They can also be attached using a bungee or strap.
Frequently Asked Questions
Titanium blades are less prone to rust than their stainless steel cousins. As a result, they require less maintenance and are lighter and stronger than stainless steel.
On the defense of stainless steel, it is also rust-resistant with the proper care and they are much cheaper.
It is important to rinse your knife with fresh water if you have been diving in a saltwater environment. Ensure it is fully dry before storing it in its sheath. If there is dirt on the blade or handle, use mild soap to clean it before drying.
Sharpen the knife as needed, as you would a kitchen knife, by using a sharpening stone, steel, or worktop easy sharpener like this one.
For long-term storage, oiling the blade helps prevent rust. There are specific dive knife oils, but a thin layer of regular household oil like olive or canola will achieve a similar effect preventing moisture from reaching the metal.
Reliability is the key here. You never know when you’ll need your knife so knowing you can rely on it when you need it is vital.
The best scuba diving knives are also strong and sharp and maintain their edge over time. Easy handling is also a key aspect of a good diving knife.
Getting your blade out quickly and knowing you’ll have a good grip when you do can be vitally important in time-sensitive situations.
Final Thoughts
- Line cutters are the safest option and are often found unsheathed as the blade is protected. This is the best choice for those who travel a lot, especially into territories where knives are controlled. They’re also a great choice for beginners who may feel nervous about carrying an exposed blade around scuba gear.
- Knives are best for confident scuba divers and are the most versatile choice. Avoid big, Rambo-style sea hunter knives and opt for a short, sturdy knife with a variety of features. Very long knives are harder to control and risk damaging your vital, and expensive, diving equipment.
- Shears are a great backup choice, there’s a reason they are popular with EMTs and firefighters, they get the job done quickly and efficiently. Carrying a pair of diving shears as well as a knife is the combination of tools we recommend. Consider getting one or several of the cutting tools we discussed in this article to help protect yourself from an entanglement.
Which are you thinking of getting? Let us know in the comments. Safe Diving.
