This was my original Sony RX100 rig built around the Nauticam RX100 housing.
The configuration had 3/4″ locline arms that proved to be a bit too stiff in water and a modified FIX ADF-PRO mount to accept Inon AD lenses.
Due to the cropping in active video I could use the Inon UWL105AD without vignetting though I had to remove the filter ring to avoid vignetting using the filter. I took this set up in Raja Ampat and worked pretty well allowing me to take mantas and pygmy seahorse on the same dive thanks to the wet lenses.
Inon UWL105AD
I then dropped this set up for a Panasonic LX7
Interceptor121 Photography & Video Workshops 
Hi Interceptor, very good blog here! Congrats.
I bought the RX 100 in in may, but i wasnt able to make good unterwater movies in the red sea… 😦
However, i am a music producer we do a lot of chillout, lounge, ambient music. I want to do some Underwater Youtube videoclips for our music. Thats why I am contacting you. A collabaration would be nice….
Sure this is of interest
I will email you separately to discuss
I would like to know the lens holder you use and how do you manage to mount it in the LocLine arm
Thanks
Read the page sony rx100 mark II compact video rig there is the whole part list