Still no confirmation that there will be housing I am compiled some of my favourite 4K videos
This is a breathtaking clips from Benjamin Todd
Another test here
There have been some rumours that the 4K mode is not a full sensor read however considering that the resolution is 4480×2520 (11M) in 16:9 and 4K is 3840×2160 this gives a crop of 1.16x there are not enough pixels to do a half line scan but the resulting angle of view seems to indicate 28mm focal length not the 26mm advertised that would give a 1.08x crop. The multi aspect sensor of the LX100 could explain why the field of view relationship changes but a 1.08x scaling seems very strange and difficult to implement. Probably something in the internal logic between sensor and lenses makes this work to have more details we need to compare the 4K still shots captured by the camera with the grabs from the video clip. Nothing on the manual seems to suggest any difference between the two so my guess this is a full sensor read.
Finger crossed that Nauticam and Ikelite produce a housing for this camera soon