I paddle my Sevylor Rio, and Advanced Elements Convertible through the everglades all the time, but even I draw the line about fishing in the ocean from an inflatable. Sharks have been known to attack boats, apparently for no reason, from time-to-time. I only use my Wilderness Systems Tsunami 175 Pro in the ocean.
A shark doesn't have to bite to damage an inflatable. Their rough hide can damage your bladders just by brushing against them. I have also inadvertently wound up in the middle of a whale pod. While I am sure they held no ill-will towards me, but they were breaching, and accidents can happen. Grant4ed, a mishap under these conditions would be no fun in a hardshell either, but I think I would have a better chance of getting through it in a hardshell. I don't even want to be around seals or dolphins in an inflatable. I have seen them get into very irritable moods before...they are bigger than me and have teeth. Alligators, I can handle...but stuff in the ocean is too much even for me.