Do I Need a Dive Knife?

First, contrary to what you may have seen in movies like “Thunderball”, underwater knife-fights don’t happen. I just needed to get that out of the way.

A lot of divers ask me this question and my standard answer is “maybe”. Honestly, I believe that every diver should dive with some kind of cutting device but a knife might not be the right tool for you. Cutting devices come in handy any time you are diving where their are or may have been people out fishing. Many of the wrecks I’ve dove have had tangled and abandoned line on them. I’ve even become entangled myself in line that had been abandoned by it’s original owner. So having a way out of situations like this is handy.

Before you start deciding on what type of tip, and how it attaches, take a step back. There are other options.

Line Cutters

Line cutters used by scuba divers

For strictly recreational divers that just want to be able to cut away any fishing line that they may get tangled up in I recommend a simple line-cutter. Most line cutters on the market have blades on either side of it’s flat surface. You are protected from the blades by the housing of the knife.

The advantage of a line cutter is that it is safe. Good ones can also cut through gear straps and webbing.

The disadvantage – if there is one – is that a line cutter is not as versatile tool as a knife. Yes, it will solve about 75% of the use-cases you need a knife for but if you run into the other 25%, you may be in trouble.

If you go with a line cutter, make sure you know what the blade is made of and that it won’t rust. A rusty blade on any tool won’t help you much.


Scissors designed for scuba diving

Next, I recommend scissors. I know a lot of rescue-trained divers and dive professionals that carry scissors over a knife. The ones available specifically for diving usually come in pouches that can be easily attached to your BCD.

Again, for most situations, scissors will get the job done. Whether it’s fishing line or your gear, a good pair of dive scissors can cut through most anything.

Like the Line cutter, they are safer to carry and use than a knife.


If you are dead-set on carrying a dive knife – I am – then you still have options to consider. No decision in scuba diving is easy.

Leg vs. BC attachment

Dive knives come in all shapes and sizes. Which one you need depends on what you are planning to do. If you are hunting and need a knife to work underwater with your catch, you need a different knife than if you are just making sure you don’t get tangled up in fishing line.

The purpose of your knife will most likely determine the size of it. The size of your knife will determine how you carry it.

Almost all of my dive knifes have been attached to my BC. I prefer the small “snap” style knives and most BCs these days come with a place to mount such a knife. These are usually a good choice, they are inexpensive, and they stay out of the way.

If on the other hand, you want a larger knife, you will need to look at one that straps to your leg. If you are not used to them, they can be a little difficult until you do get used to them. Make sure you strap it tight but not too tight and make sure you can get to it with either hand.

Stiletto vs Blunt tip

If you are considering a knife you need to decide if you need a stiletto tip (pointy) or a blunt tip. My recommendation is that unless you have a specific need for a stiletto tipped knife, go with a blunt tip. Whether you have a leg mount or a BC mount knife, getting it back into it’s sheath can be dangerous if you aren’t careful. You aren’t keeping yourself safe if you injure yourself with your tools.


Finally, when selecting a dive knife, make sure you select one that is resistant to corrosion and rust. Stainless Steel knives will rust. You will need to clean them after every dive and keep them dry to make sure they are ready for you when you need them. If your budget allows, get one made form Titanium as these knives will not rust and will hold their edge for a long time.


The bottom line is that a cutting device of some kind it a great investment for any diver. Before you rush out and buy your first knife though, think through what you need it for and see if there are better options for you.

Until next time,
Dive Confidently!

Cal “Uncle Cal” Evans

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