[FDCPR]

For me I wouldn't worry about the background, normally shooting wildlife we try to get the background unrecognizable. Normally it's just the bokeh of the shot, with a large aperture setting or using a long telephoto lens. You might be able to clear some of the haze in PP, but I personally wouldn't. Turtles are hard subjects to shoot, when they are in the water most of the time you have to shoot directly down on them, as this shot is. I've done it, as has most anyone that ever took a turtle photo. Given choices a different composition of the animal makes for a more pleasing image. The problem is that few have the equipment to put their camera underwater to capture a different perspective. That includes me also, my shots have all been similar to yours as I don't shoot in the water.

You captured a nice photo of this guy, you could have improved the clarity by adding a polarizing filter to you camera or by playing in Photoshop. But, before you spend a lot of time in PP work ask yourself: Is this a picture of a turtle or seaweed? If you answer turtle, then leave it as it is. Just my two cents, take it as you will.