Being underwater changes your perspective by letting you to enter another world. Safely doing that requires the right equipment and divers and paddlers agree knives are essential gear. Serviceable water knives are a dime a dozen but finding one that doesn't rust and stays quick-cutting sharp makes a good water knife a great water knife.

Spyderco's Caspian Salt fixed blade water knives fall into the later category. They are a solid piece of non-rusting H-1 steel. The industry's new wunderkind for watery applications, H-1 is nitrogen based instead of carbon based. Carbon rusts, but nitrogen doesn't because it doesn't interact with chloride.

Metallurgy lesson aside the knives are built around needs of people who sport in water. The Caspian comes with cutouts lessening weight with a round cutout hole fitting the index finger (even gloved) like a ring. Once gripped, dropping the knife is next to impossible without fully opening your hand. The index finger hole keeps the knife tucked deep in the palm freeing fingertips and thumb for adjusting gear, picking things up and generating leverage. The handle's solid portion is overlaid in fiberglass reinforced nylon and above the index finger hole is texturing that work together to make it even grippier- a positive feature in cold or moving water.

Two lanyard holes, on the butt end and behind the blade, create additional attachment options for a retrieval-cord or thong. The blade features a CombinationEdge™ with a line cutter set on the top of the spine. The FB21 Caspian Salt has a pointed tip. Ambidextrous injection molded Fiberglass reinforced nylon (FRN) sheath with nylon straps.