Cebu, Philippines

Just looked back at this thread and discovered your post with the missing images.  Very nice.  I've never seen a whale shark, but would certainly like to.

I only used my RX100 II for about a year (3 dive trips), so I never mastered it.  (Updated to Nikon D810 underwater, with RX100 as backup camera).

When I first shot the RX100 II, I tried using it in Aperture mode, which is my usual above-water mode for a DSLR.   I like controlling depth of field.   However, my shutter speeds were dropping way too low, resulting in a lot of blurry shots.   I then switched to Shutter priority and found good results from 1/125th to 1/200th.   I usually opted to stay at 1/160th to keep the ISO down.   I don't like the results above ISO 800.

On my DSLR, I shoot in manual mode to keep a minimum shutter speed and (especially for macro) control depth of field.    But my Nikon gives me a lot of control over ISO even in Auto ISO mode, plus it performs quite well up to ISO 3200.   I was somewhat frustrated with the Sony user interface underwater, partly simply because it was difficult to read the small print when I changed modes to even know what mode I was in.  (Unlike my Canon point-n-shoots, which announce a mode change in letters 1/3rd the size of the LCD.)    Ultimately I liked the 20mp (compared to my Canon s95), the better ISO performance of the larger sensor (compared to s95), and the ability to shoot in RAW regardless of the mode selected.    But I did not find the autofocus speed to be significantly better than a point-n-shoot, so moved (finally) on to a DSLR.

My current intention with the RX100 II is to bring it as my dive camera on non-dedicated dive trips (trips with 2-4 dives in a week) where I can easily pack the whole rig AND still have room in my suitcase for clothes.