Why Royal Navy submarine classes were theater-specific

What was the worst Royal Navy submarine type of the Second World War?

No clear worst type is identified; the greater problem was using submarines outside the environments for which they were designed.

No clear worst Royal Navy submarine type emerges from the comparison. Operational misuse often mattered more than design quality, including for minelayers sent on missions outside their intended role. U-class boats suited confined water, while S-class boats balanced North Atlantic conditions with inshore access. T-class boats supplied the size and endurance required for Far Eastern and Pacific operations.