Published by Tim Huber Oct 03, 2022

Published by Tim Huber Oct 03, 2022

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Dive knives are a scuba kit essential used by everyone from spearfishermen to technical divers to recreational scuba enthusiasts. Unlike a regular fixed blade or folder, diving knives are utilized in a markedly different environment, being purpose-built for use in and on the water. As such, even knife aficionados may find the genre somewhat foreign, making it difficult to know what factors make for a good scuba knife, what elements to consider when shopping for one, or even what a scuba knife is used for. So, with this in mind, we’ve opted to suit up, strap on our tanks, and take a deep dive into the space in this guide to the best dive knives. 

What Are Dive & Scuba Knives Used For?

Though it’s easy to assume that dive knives are primarily used to ward off sharks or other marine predators, the reality is that these blades boast a wide variety of uses both under the waves and topside. The main reason divers carry a knife is because it offers the potentially life-saving ability to cut oneself free when entangled in a net, seaweed, or fishing lines, though there’s also no shortage of supplementary uses. On top of being able to be used for prying or digging, dive knives can also be used to tap a fellow diver’s scuba tank —albeit with a dull part of the blade — in order to get their attention when underwater. Additionally, with a long enough blade, a dive knife also can serve as an anchor in the seabed. 

Scuba blades are also commonly used out of the water as well for applications such as cutting rope or lines, opening oyster shells, or gutting or preparing fish. What’s more, being armed with a dive knife ultimately affords its carrier peace of mind, knowing that, should a situation arise, they have the necessary equipment to remedy a possibly dangerous scenario. Dive knives can also be utilized in defensive scenarios against marine animals — though this is obviously in worst-case scenarios. 

The 6 Main Factors To Consider When Shopping For A Dive Knife

With dive knives being used in such alien environments, it can be a little tricky to know what elements to take into account when trying to buy one. Below, we’ve broken down half a dozen of the most crucial areas to review before making your purchase. 

Handle & Grip: With dive knives primarily being used underwater, being able to get a solid grip on the handle is absolutely essential. Recognizing this reality, most manufacturers of dive-specific knives opt for ultra-grippy handle constructions — or coatings or finishes. We also recommend opting for dive knives with a full-tang construction where the blade extends all the way to the bottom of the handle. 

Blade Construction: The type of metal used to craft a dive knife’s blade will play a major role in the overall user experience. Rather than opting for more commonly-used advanced powder metallurgy blade steels, most purpose-built high-end diving knives employ blades made from titanium or some type of stainless steel — with very few exceptions. Alongside being more expensive, titanium blades offer better corrosion resistance and are substantially lighter, though are also harder to sharpen, while steel knives are heavier though often no less strong — and are easier to sharpen and sold at more accessible prices. 

Blade Shape: Just like with out-of-water survival knives, dive knives are offered in a wide variety of blade shapes and edges. This includes everything from narrower full-length blades to shorter stubby profiles, as well as blades with straight or serrated edges (or a combination of the two). Some dive knives also feature integrated net cutters as well as blunt tips that reduce the likelihood of accidentally cutting yourself, your wetsuit, hoses, or BCD (or “buoyancy control device”).

Size: On top of a dive knife’s silhouette and edge, these items can also hugely vary in size (i.e. overall length). While different-sized knives will lend themselves to different underwater uses, scuba blades are produced in both smaller more compact packages and in full-sized models. 

Corrosion Resistance: Considering that dive knives are most commonly used in or around saltwater, the ability to stand up to rust and corrosion is beyond essential. Everything from the blade to the handle to the hardware used to piece everything together should benefit from the use of a corrosion-resistant — if not outright corrosion-proof — construction or fortifying finish. 

Sheath: Unlike regular EDC knives that are typically carried in one’s pocket or on their belt, scuba knives are almost always worn on a sheath that’s wrapped around the user’s leg or ankle — though can also be attached to a BCD or fixed to a high-pressure hose or diving belt. These factors make it important to review the sheath a dive knife is sold with, as, just like with the knives themselves, sheaths can massively vary in quality, performance, and ease of attachment and operation.

Weighing in at only 4oz, the Gerber River Shorty is a compact and corrosion-resistant fixed blade dive knife that also lends itself extremely well to other on-the-water activities like rafting and, fishing. Sold with a molded sheath with a quick-release mechanism, the River Shorty features a 3.02” high-carbon steel blade with straight and serrated edges and a blunt tip that reduces the chances of accidental punctures and cuts. Made in America, this dive knife also comes backed by a limited lifetime warranty. 

Overall Length: 6.73” Blade Length: 3.02” Blade Construction: High-Carbon Stainless Steel Handle Material: Glass-Filled Nylon

Primarily characterized by its immense versatility, the Boker Plus Steel Mariner is an eight-inch dive knife that’s also incredibly conducive to survival and outdoor applications. The knife boasts a full-tang titanium-coated 440C stainless steel double-edged blade with one side sporting a straight grind and the other featuring a serrated edge. Sandwiched between a set of grippy G10 scales, the Steel Mariner’s handle features oval-shaped cutouts that help to minimize weight while also allowing for tie-offs. Weighing in at 6.5oz, this knife is also sold with a KYDEX sheath and a belt clip adapter. 

Overall Length: 8.0” Blade Length: 4.0” Blade Construction: 440C Stainless Steel Handle Material: G10

Heavily resistant to rust and corrosion, the Scubapro Mako Titanium is a mid-sized dive knife that was designed by a team that lives and breathes diving. The knife features a full-tang construction composed of hardened Alpha titanium and a 3.34” blade that’s equipped with a straight edge and a serrated edge,  as well as a line-cutting notch and an integrated bottle opener. Alongside a kit for mounting the knife to a BCD, this titanium knife is also sold with a molded sheath that uses a unique locking mechanism that allows the user to deploy the knife with just one hand. 

Overall Length: 7.5” Blade Length: 3.34” Blade Construction: Alpha Titanium Handle Material: N/A

Made in Japan, the Spyderco Aqua Salt is a dive-specific fixed blade that’s fully rustproof. Spanning 9.33” overall, the Aqua Salt boasts a 4.69” blade that’s composed of corrosion-proof H1 steel and features a plain edge with a hollow grind, a non-reflective TiCN black finish, and a mini version of one of Spyderco’s signature thumb hole circles. The blade is mated to a textured fiberglass-reinforced nylon handle with a lanyard hole. Spyderco’s Aqua Salt also comes with an included multi-position G-Clip-equipped injection-molded sheath. 

Overall Length: 9.33” Blade Length: 4.69″ Blade Construction: H1 Handle Material: Fiberglass-Reinforced Nylon

When Conventus Ranae — Denmark’s elite frogmen and combat divers — needed a new dive knife, the outfit turned to Jens Anso and Jesper Voxnaes. Together, the two renowned Danish designers — who also cofounded boutique knife brand GiantMouse — conjured up the Vox/Anso Ranae. Built to meet the needs of Denmark’s most elite amphibious fighters, this GiantMouse dive knife is comprised of a full-tang Böhler N690 double-edge blade with a partially-serrated edge on one side and a straight edge on the other. Wrapped around the bottom of the blade is an alkaline and corrosion-resistant fiberglass-reinforced nylon handle. This knife is also sold with an ambidextrous multi-position KYDEX sheath.

Overall Length: 10.25” Blade Length: 5.25” Blade Construction: Böhler N690 Handle Material: Fiberglass-Reinforced Nylon

Not unlike the GiantMouse Ranae, the Benchmade 112SBK-BLK H20 was designed for an elite military program but has since been made available to the general public. Designed and manufactured by Benchmade in America using Austrian blade steel and a full-tang construction, the 112SBK-BLK H20 sports a 0.124-inch-thick, 3.50” blade with a blunt tip and partially serrated edge that’s crafted from Böhler N680 steel — a Vanadium and Nitrogen-rich blade steel formulated specifically for resistance to salt water. Cloaking the bottom of the blade is a rubberized overmold handle with a strategically-formulated grip pattern. 

Overall Length: 8.07″ Blade Length: 3.50” Blade Construction: Böhler N680 Handle Material: Rubberized Overmold

Just as dependable in tactical situations as it is underwater, the Toor Krypteia is the San Diego brand’s first-ever jump and dive knife. Outfitted with an ultra-beefy 0.25-inch-thick full-tang construction, the Krypteia features a 4.0″ CPM S35VN blade that’s flat-ground down almost the entirety of the spine, bolstering sharpening life. The knife also has a set of textured and notched G10 scales and jimping at the base of the blade’s thumb ramp that allows for easy reverse drawing. Paired with an included black Tru-Hide KYDEX sheath, the Krypteia is also made in America in small batches to ensure excellent quality control and ultra-precise tolerances. 

Overall Length: 8.0” Blade Length: 4.0” Blade Construction: CPM S35VN Handle Material: G10

Also made in America, the Terrain 365 Nautilus Alpha is a one-piece knife with a window handle and a 0.210-inch-thick full-tang construction composed of Terravantium — a proprietary Dendritic Cobalt blade steel that’s completely impervious to rust. Decorated in subtle laser-engraved Terravantium and Terrain 365 branding, the Nautilus Alpha also boasts an oven-cured and textured 3D-countered handle with a textured epoxy powder coating. Made specifically for use in marine environments, the knife is also sold with a TekLok-equipped KYDEX sheath.

Overall Length: 8.50″ Blade Length: 4.375″ Blade Construction: Terravantium Handle Material: Textured Epoxy Powder Coat

Born out of four years of research and development that saw Extrema Ratio collaborate with both the Italian Special Forces and law enforcement dive teams, the Ultramarine is an ultra-top-shelf dive knife that packs a 5.875″ Böhler N690 blade coated in a non-reflective and highly-corrosion-resistant Mil-C-13924 finish. Meticulously crafted in Italy, the Ultramarine was also engineered to lend itself to airborne operations and survival and combat scenarios, and as such features a 0.25-inch thickness, a partially-serrated edge, a pointed steel tang that can be used as a blunt force weapon, and a design that makes it easy to disassemble and clean. Also equipped with an integrated net cutter, this knife is sold with an ABS plastic-lined nylon sheath with a Tek-Lok attachment.  

Overall Length: 11.625″ Blade Length: 5.875″ Blade Construction: Böhler N690 Handle Material: Nylon

Still don’t own a proper dive-ready timepiece? Well, our guide to the best dive watches features more than a dozen of the finest models currently available.

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