Of course you can also try to locate them on your own if you have your own boat. This can be done with the help of a depth sounder. Generally, groupers hangout around structures that are solid. A good sounder can show you the difference between solid structures and weeds. When you locate a solid structure on your sounder; that would be a good place to try.
*Needless to say, look out for fish as well. Good sounders do show more information including fish (or things that could be fish).