Anecdotally, I've read accounts of folks who successfully used the submersion trick. Just know that typical roll-top bags will seep water with enough depth and time so count on double-bagging the contents.

I've used Ursacks for years with no issues, but have never had a bear test them either. They're not cheap but super convenient compared to rigid canisters and tree-hanging.

Cheers,
_________________________
--Rick