This is underwater test footage using a Sony Alpha a7s with a Sony Vario-Tessar T* FE 24-70mm f/4 ZA OSS Lens. Underwater housing used was the Meikon Waterproof Housing Case 40M 130ft For Sony A7 series.
My final thought is that this camera did superbly underwater and much easier to handle compared to other DSLRs I've used in the past for underwater photography and video.
Further descriptions of location, specs, etc. are at the end of the video.