Jaycen -
Have you tried using an aiming light? If the particles in the water have more contrast than your subject does, the camera will try to focus on them as contrast is what the focus looks for. Hitting your subject with some extra light should force the camera to focus there instead.
When you say you are "zoomed out" you mean that you have your camera at the widest possible lens, right? So you're seeing a bigger scene, not a close up or tight view?
Also, you may be too close to what you are trying to get a focus lock on. Every camera has a minimum focus distance and this changes with the use of the zoom. It's worth it to do a few tests on land to get a feel for exactly where you need to be to get a focus lock at various zoom settings.
Unfortunately, one of the big drawbacks with this series is the focus. Even on a bright sunny day with an excellent contrasty subject on land, mine misses as often as not. It's very frustrating and the more I use mine, the less I actually like it.
BUT - I do like the form factor and I do like that it doesn't matter if it goes in the drink or gets knocked into the sand. So I keep using it on the beach and with the dogs. I also take it out on the boat with me, just in case I see something interesting and don't want to muck with my big system in its housing.
You may need to look at a new camera if you can't find workarounds to the problems you are having, but there's no one perfect solution out there...I know, I've looked