Im a huge fan of the canon range, the powershots are good with a fair few manual controls, but they have BIG downsides! 1stly the silly slide open lens covers... not accessible in a housing, so either youre closing the housing seconds before you enter the water, to save battery, which i think could only increase the chance of floods, or open the lens, close the housing then kit up while your camera waits for you - nothin worse than running out of battery mid dive. 2ndly - AA batteries!! If you have any care for the planet (and you should, youre divers) get a camera with a lithium-ion battery. A weeks diving means about 40 dead batteries to dispose of.
And for those 2 reasons and more i chose the ixus 85 (possibly called something else in usa) . An amazing small camera with good high, quality lens. a small housing and good battery life in a Li-ion. The bit that swayed me over Olympus, pentax, fuji etc was the ability to set the direct print button to an option of your choice - of course UWP's will choose the custom White Balance! So 1 button to set your WB is amazing, no fidly menus etc. Macro also goes down to 4cm and digi macro to about 2 but no flash fires with digi macro.
Canon have updated the ixus 85, with the 90 and added to the range with 870 and 970 etc but they added a silly wheel to get to some manual menus which, of course, you cant get to in the housing so some options just not available UW. a pity with the expanded screen and better MP count.
Anyway, the 85 is great camera. ive added a stobe, a macro lens for super close ups and WA lens too.
Im off to the philippines in 3 days for a long dive trip so maybe i'll post some pics in the contest soon!
Olly