Sounds like the Oberons excelled at intelligence gathering getting up close underneath other subs/ships and getting underwater images of what couldn't be seen from the surface and also recording acoustic signatures.
There are some other fascinating history bits I found (open source) about submarine deployment diaries. I'll have to see if I can find that again.
Based on this guy's videos - I think that the RCN should download them, and play one a day on the SONAR OP course, and replace the daily SONAR sitrep brief in the OPS room at sea with these....the history that he turns up on the RU navy's deployments is incredible.
20 years ago, these videos would have been probably SECRET or TS SA info.