Hi, don´t want to steal you thunder as I might be wrong, but from what I know the WWL-C is not designed for FF bodies (it will display vigneting probably). You could run your Z8 in aps-c mode (with a standart zoom aps-c lens) or it is probably more apropriate to get the WWL-B or WWL-1. From my expirience when snorkeling with whale sharks, most of the encounters are quite short (like 5s in a position to get a good shot) and you get in and out of water a lot. Clearing bubbles seems to me like a great complication that can be avoided by either a dome port / WACP / action cam.