A dive knife is an essential part of dive safety and not a weapon. Dive knives come in a wide variety of materials, styles and sizes.
My response is my knife is one of my most utilized pieces of equipment. First and foremost for cutting free of entanglement, but also for dispatching struggling fish after they’ve been speared to avoid attracting sharks. People have been known to avoid shark attacks by utilizing their knives as a method of defense. A knife can be used for cutting chum/burley to attract certain species of predatory fish. Some divers even use their polished stainless knives as a lure to attract fish.
Dive knives come in either stainless steel or titanium.
Stainless Steel diving knives:: typically cost less than titanium dive knives and are generally suitable for most recreational diving environments. Stainless steel dive knives are typically made from either 300-series stainless steel, such as 304 SS, or 400-series stainless steel, such as 420 SS. In general, 300-series stainless steel is more corrosion-resistant than 400-series stainless steel, but is softer and will require more frequent sharpening. 400-series stainless steel is harder and will stay sharp longer, but is more susceptible to corrosion and will need to be cleaned thoroughly after diving in salt water.
Titanium dive knives::are lightweight, strong and highly corrosion-resistant, making them perfect for diving. Although titanium dive knives typically cost more than comparable stainless steel dive knives, they require little maintenance and stay sharp much longer.
When buying a dive knife, also buy the knife holder to strap on your leg. This is convenient and will be quick to grab when needed.
Kathy Dowsett, Owner and Operator of