Regardless of which type of scuba diving you’re interested in from wreck diving and cave exploration to simply taking nice tropical fish pictures a dive knife is a recommended accessory. Ghost nets and other objects can be dangerous if you get entangled in them and having a knife with you that can help you free yourself is therefore highly recommended. When taking tropical fish pictures you may for instance become so absorbed by your task that you don’t notice that large ghost net stuck on the outside of the ship wreck where the most spectacular lionfishes are playing peek-a-boo with your camera. In such a situation a good dive knife will help you free yourself from the net before things get critical.

You should consider the following things before buying a dive knife

- Choose the right scuba knife; one that suits you and your particular needs.

- Make sure that you know how to use the kind of dive knife you choose to get. A sharp knife in the hands of an insufficiently prepared diver can cause more damage than what it prevents; especially in a panicky situation.

Below you will find info on how to choose a knife that suits you.

Size matters

There are three main sizes of dive knives, big knives, mini knives and standard sized knives. A standard size dive knife, also known as medium size dive knife, has a 4-5 inch or 10-15 cm blade and is small enough to comfortably keep mounted on your leg, arm or BC. Make sure the handle is large enough for you to grip without much ado. Mini Knives are 2-3 inches (5-7.5 cm) and can be mounted on the air tube. Unfortunately, many of them come with handles that are difficult to grab underwater, especially when wearing diving gloves. Always test the handle prior to purchase. Any knife with a blade that is longer than 6 inches (15cm) is ti be considered big and can though to handle with any degree of precision under water. When scuba diving, big doesn’t automatically equals better so only get a big scuba knife if you know that you will be doing things underwater that actually require a big knife.

What material should the knife be made from

Most dive knifes are made from titanium or stainless steel. Titanium knives are the best most durable choice but it is also to most expensive option to buy, they can howeverbe cheaper in the long run as they last a lot longer than steel alternatives. A stainless steel knife will on the other hand be more susceptible to rust and corrosion, but you can counteract this by rinsing it off in freshwater after each dive and leave it to dry completely before putting it back in its sheath. Coating it with a layer or oil or silicone is also recommended.

Serrated edge or not?

A serrated edge is ideal for cutting natural fibres such as hemp ropes and kelp, while a straight edge will be more apt at cutting artificial materials like nylon ropes and monofilament fishing lines. Serrated knives with serrations along the entire blade is better as that make is easier to use it as a saw. I recommend that you get a knife witha serrated edge on once said and a straight edge on the other, that way you get the best from both worlds.

Should I choose a knife with a sharp tip?

Sharp tips are popular among spear fishers, but if you plan on using your knife for something else then a blunt tip is usually to be preferred. The reason that ablunt top is usually better is that a sharp tip easily breakes when using the knife to dig and pry. Having a knife with a sharp tip will also increase the risk of accidently puncturing a BC your own or your dive buddy’s.

Do I need a line cutting notch?

Yes, a cutting notch will make it much easier to cut small lines and other potential dangers.