A diving knife is a useful tool for all divers, not just technical ones. It helps free divers and gear from entanglements like seaweed and ropes. Dive knives can have fixed or folding blades, and are made from materials like stainless steel or titanium. It’s important to clean and store your knife properly to prevent rust, and check local laws before taking it on dives or flights. When choosing a dive knife, consider its size, how you’ll carry it, and the type of diving you do.