I've seen magazine reviews tell divers the serrated edge on a dive knife is useful, but I wonder? If you've ever really tried to saw/cut a 3/8" or larger diameter waterlogged rope underwater with the serrated edge of a dive knife you'll know what I mean. Two weeks ago, after Rodale's Scuba Diving magazine's knife review jogged my interest, I tried it again, this time on a sunken fishing net with a 1/2" waterlogged hemp rope on it. The serrated edge was next to useless and this was on a nearly new dive knife. On the other hand, the business edge, which I'd sharpened with a file in a forward stroke from tang to tip, did eventually cut thru. On another point, divers might want to consider a blade with a "guthook" on the top edge near the front end. On hunting knives, the hook is there specifically to catch and slice small line which is the most dangerous type of snag we generally run into.