Is a small knife enough for spearfishing?

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Knives for Spearfishing

Knives for spearfishing designed to ensure safety, reliability, and practicality at sea. Ideal for handling your catch and quickly cutting lines, nets, and monofilament, with belt, arm, or calf attachment.

Spearfishing Knives

The knife is one of the most important tools a spearfisher takes into the water. It is not a secondary accessory: in some situations, it is the only means available to free yourself from a tangled shooting line, cut a snagged line, or dispatch a caught fish quickly and safely. Choosing the right knife is not just about aesthetics or price: it involves blade type, steel type, body positioning, sheath quality, and the fastening system.

In this category you will find a selection of spearfishing knives divided by positioning, type of use, and price range. The products come from Italian and international brands with proven experience in the sector, with a catalog ranging from compact arm models to professional fillet knives. The assortment includes over sixty items, with options for beginners and for those who practice spearfishing consistently and technically.

Types of Spearfishing Knives

The main distinction concerns body positioning, which determines accessibility, bulk, and type of use. In this category, products are classified into four main macro-types, along with related accessories.

Belt Knives

They are the most common type in spearfishing. They attach directly to the belt, remaining accessible by hand. Blade lengths generally range from 9 to 14 cm. The sheath must feature a reliable retention system that prevents the knife from slipping out accidentally during dives while allowing quick one-handed removal. This category includes numerous belt models from brands such as Salvimar, Mac Coltellerie, Cressi, Beuchat, C4, Mares, and Rob Allen.

Arm Knives

They are positioned on the forearm using elastic or neoprene straps. The arm knife is easy to reach and reduces bulk at the waist. C4 and Salvimar produce dedicated arm straps, compatible with the main models from the various brands.

Calf Knives

Calf positioning is appreciated by those who want to clearly separate the belt area from their safety equipment. It is secured with adjustable straps below the knee. This setup requires the knife to be safely removable. Many belt models in this category are also classified as calf knives thanks to the sheath’s compatibility with different mounting systems.

Fillet knives

They have a long, thin, flexible blade with a sharpened edge on one side only. They do not replace the safety knife but are used after the spearfishing session, on board, on shore, or in the kitchen, to fillet the catch. The flexible blade allows you to work close to the bone without wasting meat. This category includes fillet knives from Salvimar and Mac Coltellerie, with blades featuring dimensions and profiles specifically suited to this function.

Specialized cutting tools and accessories

The assortment is completed by several purpose-specific tools: knife straps for arm mounting, Mac Coltellerie and Imersion sea urchin cutters, safety line cutters such as the Twin Rescuer TS09 by Mac, fillet knives in various sizes, and sharpening stones for routine blade maintenance. These tools meet specific practical needs and complete the spearfisher’s kit.

How to choose a spearfishing knife

Your choice should start with the actual use you expect from the knife, the type of hunting you practice, and how you prefer to carry it during the dive.

Safety first

A spearfishing knife is first and foremost a safety device. It must be quick to draw with one hand, even while wearing neoprene gloves. The sheath must hold the knife securely during dives and surface swimming, preventing accidental loss, while still allowing immediate release when needed. A knife with a hard-to-release sheath loses part of its value in an emergency.

Plain, serrated, or double-edge blade

The plain-edge blade cuts cleanly and is easier to sharpen. The serrated blade is more effective for cutting lines, braided cords, fishing lines, and nets, even when the blade is not perfectly sharp. Many models combine both types on the same edge or on two separate sides of the blade. The Torpedo Knife by Mac Coltellerie, for example, features one plain edge and one serrated edge, as do several Salvimar models in the Atlantis series and Predathor line.

Blade dimensions

A blade between 7 and 12 cm is the most functional size for spearfishing. Shorter Blades are easy to handle and compact; longer Blades offer greater cutting capacity, but can be uncomfortable to carry on the arm or calf. The Sigal Sub Storm and Kenobi knives feature 7 cm Blades, while the larger models in the Salvimar Atlantis line go up to 10 cm Blades.

Placement and attachment system

The choice of placement depends on the gear used and personal habits. Those who use a belt loaded with accessories may prefer an arm or calf setup. For most spearfishers, belt placement (on one side) is the preferred position due to its accessibility. The sheath attachment system—clip, strap, or cord—should be checked in practice before every session.

Materials and technical features

Almost all spearfishing knives in this category use stainless steel as the blade material. However, not all stainless steels perform the same way in marine environments.

Always keep in mind that good steel, with a good hardness rating and therefore good edge retention, will necessarily have a higher carbon content, which will cause the blade to oxidize if not properly cared for.

Stainless Steel and surface treatments

The most common steel grades used in dive knives are AISI 420 and W 1.4116. Both offer corrosion resistance in marine environments, but still require rinsing with fresh water after each use to extend blade life. Some models, such as the Mac Coltellerie Torpedo, feature a black IDROGLIDER GOLD® coating that adds resistance to surface oxidation and reduces blade reflectivity underwater. The Kunai Knife also uses a dark surface treatment on the blade.

Handle materials

The handles of the knives in this category are mainly made from engineering polymers such as TPE (thermoplastic elastomer), ABS, and neoprene overmolding. These materials ensure a non-slip grip even with wet gloves. Some models, such as the C4 Ronin line, are available in several colors — white, red, black — making it easier to identify the knife in case it is lost. The Salvimar Predathor and Goemon line is also available in multiple colors, including acid green and military green for those who prefer a camo colorway.

Sheaths and retention systems

The sheath is an integral part of knife safety. The models in the catalog use rigid polypropylene (PP) sheaths with drainage holes, which prevent water from accumulating inside. The retention system varies: some models use a spring-loaded pressure clip, while others use a button system. Salvimar offers separate knife straps — the Krypsis Strap and the Large Elastic Strap — for those who want to replace the original attachment or adapt the knife to different positions on the body.

Practical use

In spearfishing, the knife comes into play in three main situations, each with different requirements.

The first is to dispatch the fish: after the catch, it is necessary to quickly end the fish’s suffering. The most effective way is to reach the brain. This requires a sharp tip and a blade that is not too thick, in order to penetrate precisely without excessive force.

The second is active safety: in the event of entanglement in float lines, abandoned fishing lines, ghost nets, or other hazards, the knife must be able to cut quickly without requiring wide movements or high force. For this reason, many spearfishers carry two knives — a main belt knife and a smaller arm-mounted one — so they always have a cutting option within reach regardless of body position. The Mac Twin Rescuer TS09 is designed specifically for this function: it is a dual curved-blade safety line cutter, not a conventional fishing knife.

The third is preparing the catch on shore or on board: filleting knives with long, flexible blades are used to break down the caught fish into fillets. The Mac fillet knives in the D300, D305, D308, and D310 series are professional tools with blades of different lengths for working on fish of different sizes. The Mac sea urchin cutter and the Imersion version, on the other hand, meet a specific need in Mediterranean coastal spearfishing.

Available brands

Salvimar is the brand with the largest number of items in this category, with over twenty models including knives and accessories. It offers complete lines with multiple color variants — Predathor, Goemon, Atlantis, Ares, ST-Atlantis, ST-Blade — covering a wide range of prices and uses. The Krypsis knife straps and the Large Elastic Strap complete the accessory offering.

Mac Coltellerie is an Italian company specializing in the production of knives for underwater use, with the widest range in terms of variety: belt and calf-mounted spearfishing knives such as the Mako 2, Torpedo 9, Sub 9, Sub 11, Microsub Race, and Shark 9, alongside a complete line of fillet knives, sea urchin cutters, and maintenance accessories such as sharpening stones.

C4 offers the Ronin knives (available in white, red, and black) and Naifu / Naifu S, with sheaths and 4 mm knife straps produced separately. They are compact models designed for spearfishing and freediving.

Cressi is present with three models — Lizard, Finisher, and Predator — positioned in the mid-range segment and featuring ergonomic handles and sheaths with push-release systems.

Beuchat offers the classic Mundial 2, a double-edged knife with a high-grip handle and attachment compatible with a Marseillaise belt, historically valued for the quality of its locking clips.

Rob Allen is present with the Knife Dentex, a rugged South African-made model with a long stainless steel blade and a rigid sheath with a mechanical retention system.

Sigal Sub offers three models — Storm, Kenobi, and Razor — with short 7-8.5 cm blades, compact construction, and magnetic retention on the Storm model, a solution that allows quick extraction without operating the locking system.

Mares is represented by the Snake 2.1 and Hero Polygon models (in standard and short versions), with high-contrast ergonomic handles and stainless steel blades.

H. Dessault is a French brand present with the Knife Master, positioned in the mid-range segment.

Imersion contributes the Size Ricci Standard, a specific tool for harvesting sea urchins, while Best Divers is present with the Knife Shogun, an entry-level model.

Deep Blue offers the Kunai knife model, produced with a dark treatment on the blade.

Conclusion

The selection of spearfishing knives available at DEEP BLUE covers every freedive spearfisher’s needs: from active safety during the dive to professional fish preparation, as well as specialized tools such as sea urchin cutters and line cutters. With more than sixty items organized by placement and function, and with brands such as Salvimar, Mac Coltellerie, C4, Cressi, Beuchat, Rob Allen, Sigal Sub, Mares, and others, you can build a complete setup that matches your fishing style, conditions of use, and configuration preferences. The knife-use filter — arm-mounted, belt-mounted, calf-mounted, fillet knife — lets you quickly identify the models best suited to your needs.

Frequently Asked Questions

In spearfishing, a knife is primarily a safety tool. It can be used to cut shooting lines, nets, ropes, monofilament, or other items that may create dangerous situations underwater. It is also useful for handling the fish after the catch.

Often, yes. For most outings, a compact, well-sharpened knife is more than enough: the priority is that it is accessible, secure in its sheath, and truly effective at cutting.

In spearfishing, the compact size makes positioning and carrying easier, and it is absolutely adequate for dispatching small fish. However, when fish get larger, or when the risk of getting entangled in nets, lines, or debris on the bottom increases, a long, razor-sharp blade becomes an essential requirement.

Technical stainless steel offers good cutting performance, durability, and a balanced price. Titanium is more corrosion-resistant and very lightweight, but usually comes at a higher cost. The choice depends on how often you use it, your spearfishing environment, and the level of maintenance you want to dedicate to the knife.

For spearfishing, it is best to choose a compact, lightweight, corrosion-resistant knife that is easy to draw even with gloves on. The blade should be sturdy enough to cut shooting lines and ropes, but not so bulky that it interferes with finning and trim.

Yes. After every trip at sea, it is important to rinse the knife with fresh water, dry it thoroughly, and check the blade, sheath, and locking system. Even knives made from high-quality stainless steels generally contain a percentage of carbon that contributes to cutting performance, but can promote the appearance of slight oxidation if exposed to the saltwater environment for extended periods. For this reason, rinsing with fresh water is essential to limit oxide formation and preserve the knife’s efficiency over time. Even the most corrosion-resistant materials benefit from simple but regular maintenance.

The knife can be attached to the belt, arm, calf, backplate, or other points on your gear. The most important thing is that it stays secure, does not restrict movement, and can be reached quickly even in an awkward situation.