I have that camera (CX550) in a BF housing and it over exposes badly compared to other Sonys I have had.
Best results I find when shooting auto is to set the Auto Exposure (AE) shift to -3 though occassionally I will still need to set the exposure to manual and crank it down till it looks good in my monitor.
It also is a little too warm for my tastes tending to over boost the reds so I have also adjusted my White Balance (WB) shift to -2 or 3 depending.
I will usually do a manual WB before recording.
On the plus side, this probably has the best auto focus of any I've used though it may "seek" (blur) in lower contrast subjects as most do.
Setting manual focus is best but for close subjects it is amazing how well the auto focus works.
Other posts cover setting the manual focus.
Hope that helps.
You can get very nice results with this camera but have to practice a lot to find what works best.
Thanks for the reply. I will try the Auto Exposure as you suggest. Will a neutral density filter help? In addition to having to much light, there's also a strobe like effect from the light refracting through waves and off the bottom.