I had some problems with my z240 this year and so was strobe-less for the season, so all the photos are ambient light (except the sculpin - was lit up with a dive light) and just bumped ISO. High ISO performance is great, the tuna was darting in and out and I was at around 30 feet, but still managed to freeze him with decent quality.
None of the photos are cropped, all post processed:
(it was a very pinniped-heavy year)
Overall I'm very pleased with the camera, the IBIS system is awesome for doing any kind of active video shooting, and the whole rig (camera PLUS housing) is light and small enough for me to even take backpacking (something I would never have considered with my old 40d/hugy). I had a bit of buyers remorse after comparing video specs on similar 4/3 cameras, but I'd have to say the image stabilization was the deal sealer after the results came through - I can walk around canyons and trek through water and with a little bit of effort the footage comes out as if on a moving pan-head.
You can imagine the same benefits this results in underwater.