leatherman Wave for inshore stuff, lots of good tools. I carry it offshore as a tool.
On my PFD I have this:
Last thing I want to do when I need a knife NOW, is open the blade. Also, a quality straight blade is always stronger than a folder. Put some T9 on it or a dab of oil on a cloth and wipe it down. 316 stainless won't hold an edge very long. Look for a knife with a high carbon content. It will rust a little, but preventative maintenance should solve that issue.