filter recommendations

I am going to be purchasing the pt-014 housing for my oly c-50 zoom. I am a beginner, so I am looking for info to help me achieve the best possible shots. My first few trips will be snorkeling in the carribean. I am also planning on a few fresh water dived this summer in some inland lakes and the great lakes (i am from michigan).

What types of filters should I use for the carribean to get my best colors? What about for frshwater? I am assuming I will need an external strobe for deep dives, and possibly in some of the shallower inland lakes due to lower visibility.

what about exposure settings? Do most people always use the macro feature underwater?

For shallow water a filter isn't really necessary. It depends how deep you go on snorkle. Fresh water tends to be green compared to the carribean but a green water filter is useful for shallow blue water diving as well. See this article for more information on filters.

If you use a filter and no flash you can start out using autoexposure.