The jail was designed to hold 318 inmates but the Howard League for Penal Reform says at the end of January, there were 530.
The charity also says the overcrowding leads to more violence and self-harm among prisoners, and hampers their rehabilitation.
Poisonous trees near park may have to be removed
Plymouth council is consulting the public
Plymouth's £750 million debt is good for city, council claims
Leaders say money is used for investment
Drydon Road traffic scheme: you help decide
Council changed layout during covid
Three injured in Plymouth street fight
Police are appealing for witnesses
Pedestrian dies in Brixham crash
Articulated lorry involved
Body found at Sandy Bay
It's after two men went missing on Christmas Day
