I don't think most of the underwater single-use cameras dive deeper than 15 feet or so.
I actually really like the idea of a SWC in housing with a 70mm roll back. That would be pretty cool once you got the hang of it. Of course, I can't afford diving let alone the camera. :)
How about the Nemrod Metzeler S.A. Siluro-S a 6x6 underwater camera made of Novodur plastic in the 1960s, the Leicashop in Vienna has one for sale https://www.leicashop.com/vintage/ne...os-p-5105.html
the camera looks pretty simple according to camerapedia one shutterspeed and a fixed focus lens and requires a flash http://medfmt.8k.com/mf/nemrod.html
A 35mm UW camera is a better choice and the older Nikonos or Sea & Sea cameras can be bought quiet cheap.
We all Just missed the deal of the decade...an aquatica 67 housing just sold on ebay for 407.00 us. One of 50 made globally, the only other for sale housing is from Mauricio Handler is 4K. Only works with Mamiya Pro II and winder motor or digital back. What a special item to even get to see.
Keep in mind you can't reload your film until you finish your dive.
Rolleimarine if you can find one
Pentax made a complete underwater housing system for their 6x7 camera and certain lenses. But they were never common, and the seals on
old ones might be difficult to replace. Still, it was an ergonomic camera which handled like a giant 35mm SLR, and you might stumble onto one.