All the machines listed on the post are good choices. But remember , all the machines recommended except the
Garrett AT Pro are NOT waterproof ! Some are "Weatherproof" like the Fisher F44, (Weatherproof. Meaning a little rain).
But with all these machines if you slip and dunk them say good bye.
Are you happy with your Tracker IV ? I love mine. its as waterproof as all the machines listed above except the AT Pro.
If your serious about going into the water, I agree with some of the other guys. Save a couple extra bucks and get the machine that fits the kind of hunting you dream about.
My suggestions ; Garrett AT Pro, Whites MX Sport, Equinox. All in the $ 500 to $700 price range new, $300 to $500 used.