For underwater cases try these people
camerasunderwater
They have the largest range I have found in one place, find the camera you like than have a look & see if they have a case for it.
Like Richard B I have been using a Cannon for some years & so has my son, I still have the A10 & my son now has the A70. These cases are very robust they have been bounced around in our clubs dive rib, & even had weight belts & cylinders dropped on them.