With the MJU720SW, it is more or less a point and shoot camera, but you do have choice of ISO settings in program mode, plus you can get a 4-5 secend exposure by using the Night-time setting, but other than that no manual adjustment, but as you can see from the two images that I posted with some experimenting with lighting you can get decent images out of these cameras (But NOT every image).
The next best thing to this camera is my Canon G7 which has full manual control, but is not waterproof, and when it is in it's waterproof housing it is the same size as your Nikon D70S.
I also use a Nikon D70 underground, but only when I'm going on a specific photographic trips.