A dive knife isn't a weapon — it's an entanglement tool. Fishing line, kelp, rope, and netting can wrap around you, your buddy, or your gear without warning, and a cutting tool is the fastest way to free yourself. Every diver who dives in environments with potential entanglement hazards (which is most environments) should carry a cutting tool.
Knife Types: Blade, Shears, and Line Cutters
Traditional dive knives feature a stainless or titanium blade, typically 3–5 inches, with a serrated edge on one side and a smooth edge on the other. They're versatile but bulkier than specialized tools.
Dive shears work like heavy-duty scissors. They cut line, webbing, and thin rope more safely than a blade because there's no exposed cutting edge pointing outward. Popular with technical divers and instructors.
Line cutters are compact, hook-shaped tools with a recessed blade that slices monofilament and thin line without risk of cutting anything else. They're the smallest option and fit in a BCD pocket or clip to a D-ring.
Top Cutting Tools
Atomic Aquatics Ti6
A full-size titanium dive knife that will never rust, corrode, or need sharpening as often as stainless. The six-inch blade handles everything from monofilament to heavy kelp. Comes with a quick-release sheath that mounts on a BCD, leg strap, or console.
Scubapro Mako Knife
A compact, affordable dive knife with a 3.5-inch stainless blade. Serrated and smooth edges handle different cutting tasks. Small enough for a BCD pocket or forearm sheath. A no-frills cutting tool that does the job for recreational divers.
Eezycut Trilobite Line Cutter
A tiny, purpose-built line cutter that clips to a BCD shoulder strap and slices monofilament, braid, and thin line with a hook-and-pull motion. The recessed ceramic blade can't accidentally cut you or your gear. Widely carried by tech divers as a backup cutting tool alongside a primary knife or shears.
Maintenance
Rinse your knife or cutter in fresh water after every dive. Stainless blades benefit from a light coat of silicone grease on the blade and sheath mechanism. Titanium blades require virtually no maintenance beyond rinsing. Check the edge periodically — a dull knife is more dangerous than a sharp one because you apply more force to cut.