Have been in Cocos recently and never before had a problem like this:
when recording video after some minutes I got a fogging lens and/or dome port inside. This behavior did not occur when shooting stills. Nikon DSLR in a Subal aluminum housing with a 9 inch dome port.
I guess this has a lot to do with the humidity of the environment. as a matter of fact it was very rainy in Cocos all the times and thus very humid. I always prepared the housing on the sun-covered camera deck of the boat (Sea hunter) but leaving the housing sometimes open during the night (covered with just a towel). So by this I guess it accumulated humidity from the air and when recording underwater the upheating of the camera created the fogging.
Any other ideas or experiences like that? Am I right with my assumptions? Should I have always prepared the camera in an AC-controlled environment like inside the ship?