If anyone bothered to read:
I also scuba dive and a very popular knife in the tech diving community is a modified steak knife. It's cheap ($2), sharp, rust proof, and easily replaced.
SCUBA. I never said that I do or would use this knife and certainly not in that sheath. It would be lost BEFORE your first swim. Oh, and check out the link in that post.
My point was that there may be alternatives to the $50 knife you may lose anyways.
I do agree; Knifes are a must for paddling. How else can you cut up that apple after a hard playboating session.