General Requirements
A good survival knife should not be a Rambo-size sword regardless of what Hollywood says. These knives are typically too large and heavy to carry, and pose more risk for injury from use than they are helpful. Blades should be 4 to 6 inches long, and are typically made of stainless steel or carbon steel. Stainless will not hold an edge as well, but holds up in extremely wet or corrosive environments. Carbon steel holds an edge better but is more susceptible to rust. Knife blades will also come in smooth or serrated. Smooth blades offer more overall cutting surface and are easier to field sharpen. As seemingly nice as it may seem to have the extra cutting power of serration in the field, the truth is that the need does not often arise. Also, it is extremely difficult to sharpen serrations in the field. A smooth blade is more easily sharpened and may be done so with rocks.
Fixed Blade Knives
When choosing a fixed blade knife, some of the best and most recommended knives come from the Ontario Knife Company. These knives are designed for survival and feature good blade lengths, handle materials specifically designed for a good grip in wet or dry conditions and various designs for personal choice. Ontario knives are used by various U.S. Government and military groups. Another good choice in a fixed blade is the SOG SealPup. This knife is a smaller version of the SOG Seal and is constructed to withstand the abuses of diving as well as survival. Weighing in at just under 5 ozs., this is an excellent choice for packing. The Gerber LMF 2 is a relative newcomer to the market and was designed in conjunction with the U.S. military. The LMF 2 features a full tang blade, comfortable handle., and excellent cutting ability. The knife was specifically designed to aid in extrication from downed aircraft or wrecked vehicles.
Folding Knives
Although folding knives are not considered as strong as fixed blades, there are several knives to be considered for survival. The Benchmade Vex is a straightforward knife from the Red Class of Benchmade knives. The Red Class is the lower and less expensive line from Benchmade. However, the Vex contains features of knives costing $100 more. Featuring a rock-solid blade design with liner lock, the blade is over 3 1/2 inches long, is carbon steel and features a titanium nitrate coating for protection. The knife also features G10 scales for superb grip. The Cold Steel company makes the Recon 1. This knife features a blade made from AUS 8 steel that is durable and holds an edge well. The blade is just under 4 inches long, and the scales are G10 material for gripping ability and durability. This is a tough-as-nails knife that is rock-solid when open and is up to a variety of cutting chores.