Best Dive Knives (And When You Actually Need One)

Despite what you've seen in the movies, a dive knife is not for fighting sharks.

It's a safety tool. Divers have died getting entangled in fishing line, nets, and kelp when a cutting device would have saved them. I've been tangled in fishing line myself diving in Miami, and having something to cut with is not optional.

As a PADI Divemaster with five years of diving in Florida, I carry a cutting tool on every single dive. Here are the four options I recommend, with a buying guide at the end to help you pick the right one.

Best Budget Knife: Cressi Skorpion

The Skorpion is the first knife I recommend to any diver looking for a reliable all-around option without overspending.

The 4.75-inch blade covers serrated, smooth, and line-cutting functions in one tool. Fishing line, kelp, nets, webbing. It handles all of it. The special coating helps the stainless steel resist saltwater corrosion, though stainless will still need maintenance over time.

The molded rubber handle fits comfortably in most hand sizes and includes a tank-banging tip. The sheath releases with one hand, which matters when you're working quickly underwater. Two rubber straps attach it to your arm or leg.

Not the most low-profile knife on this list. But at this price, it's the most capable all-around option.

Best Premium Knife: SCUBAPRO Mako

If you want to buy one knife and stop thinking about it, the Mako is the one.

The titanium blade doesn't rust, holds its edge longer than stainless, and weighs almost nothing. At 3.5 inches it sits low against a BCD strap or thigh without getting in the way. It has serrated, smooth, and line-cutting edges in a significantly more compact package than the Skorpion.

The push-button sheath lock is more secure than most clips, and the handle is ambidextrous. The tip doubles as a tank banger and a bottle opener.

At ~$149 it's the most expensive knife here. Titanium costs more. It also lasts longer and asks less of you in terms of maintenance, which over the years makes the price gap smaller than it looks.

Best Line Cutter: EEZYCUT Trilobite

The safest cutting tool you can carry, and the one I'd hand to a beginner before anything else.

The blade faces backward inside a guarded housing. You cannot accidentally cut yourself, your hoses, or your buddy. You can clip this to your BCD strap unsheathed and forget it's there until you need it.

It cuts through fishing line, nets, and scuba webbing cleanly, and can go through a drysuit if needed. The one limitation is thickness: nothing over 0.47 inches. That rules it out for kelp forests where you might need to cut through something more substantial.

Under $30, travel-friendly, and allowed in countries where carrying a knife is restricted.

Best Shears: Cressi Trauma Shears

EMTs and firefighters use trauma shears because they cut through almost anything fast. The same logic applies underwater.

These shears handle netting, straps, and drysuits without hesitation. They come in a nylon pouch that threads onto a waistband, strap, or BCD pocket.

The tradeoff is maintenance. Saltwater gets into the scissor mechanism and causes rust faster than with a knife blade. Rinse thoroughly after every dive, dry completely, and oil the hinge regularly. Expect to replace them more often than any knife on this list.

Carry these as a backup to your primary knife, not as your only cutting tool. Together they cover every scenario you're likely to face underwater.

Dive Knife Buying Guide

Knife vs Line Cutter vs Shears

Knives are the most versatile. They handle line, kelp, netting, and equipment with a sharp or serrated blade. Best for experienced divers comfortable handling an exposed blade near their gear.

Line cutters have a protected blade that can't accidentally cut hoses or fingers. The most safety-conscious option and the best choice for travel.

Shears cut fast and cut everything, but require more maintenance and are best used as a backup alongside a knife.

Tip: Sharp or Blunt

Sharp tips offer more precision and are preferred by spearfishers and experienced divers. They're also more likely to damage hoses or equipment in an emergency if you're not careful.

Blunt tips are safer around gear, better for prying, and the right call for most recreational divers.

Blade Edge: Serrated or Smooth

Ideally both. A smooth edge cuts through plastic and line cleanly. A serrated edge saws through kelp, rope, and natural materials more effectively.

If you can only have one, serrated is the more useful choice underwater.

Size

Stick to 3 to 5 inches. Bigger knives are harder to control, more likely to snag on gear, and no more effective for what you actually need. A compact knife you can access quickly is more useful than a large one that gets in the way.

Attachment

BCD or hose-mounted is the most secure option and the least likely to be forgotten. Rinse the mount after every dive.

Leg-mounted knives offer quick access but can snag or loosen from the sheath. Check the lock before every dive.

Foldable knives stored in a BCD pocket are the safest carry option for travel and work well with a bungee or clip.

Color

Bright colors make the knife easier to find if you drop it on the seabed and easier for a buddy to grab in an emergency. Visibility is a functional consideration, not an aesthetic one.

Do You Actually Need One?

If you're a beginner diving with an instructor or divemaster, they're already carrying one. You don't need to buy one immediately.

Once you're leading your own dives with a buddy, or diving solo, carry at least one cutting tool, and ideally two: a primary knife and a backup line cutter or shears.

Some countries require divers to carry a knife by law. Check local regulations before diving internationally.

How to Look After Your Knife

Rinse with fresh water after every saltwater dive. Dry completely before returning it to the sheath. Clean the blade and handle with mild soap if there's visible dirt.

Sharpen the blade as needed using a sharpening stone or a standard kitchen sharpener.

For long-term storage, apply a light coat of oil to the blade to prevent moisture from reaching the metal. Dive-specific oils exist for this, but a thin layer of olive or canola oil achieves the same result.