As long as its not bead blasted 14c seems to be pretty good around fresh water, the amount of belly on that blade though would be a poor choice in my opinion for a water rescue knife. If you are intending on cutting rope, or webbing (like on a pfd strap) or neoprene (like on a spray skirt) serrations help quite a bit, and the less belly the better, as it will tend to have the item you are trying to cut roll off the edge without being cut. The amphibian really is pretty well designed, models to look at would be the 1078 responder, 1028 antelope hunter, or even the 1008 sea hunter (a bit big for most uses)
For my use on river everyday nothing short of H1 steel holds up well enough corrosion wise (a serrated hawkbill folder), but for the occasional use, 14c aught to be great, and 420 would also be very corrosion resistant.
It comes down to what exactly is your use for the knife?