HMP Humber is still 'not safe enough' and 'managing considerable risks' according to a report by prison inspectors.
They carried out the unannounced inspection at the end of last year and found 'high levels of victimisation, intimidation and violence, some of it serious' among the 1,000 inmates.
However, there was also praise for the governor and staff, saying the prison was well led and staff were committed - and there was good reason to be optimistic about its future.
Nearly two-thirds of prisoners at the Category 'C' jail at Everthorpe, East Yorkshire, thought drugs were easy to obtain and three in 10 claimed to have acquired a drug problem while at the prison.
The report says evidence suggested that much of the violence was underpinned by a pervasive drug culture.
Drug testing data suggested a positive rate – when psychoactive substances were included – of 38%, which made clear the extent of the problem.
It also stated that the extent of vulnerability was arguably reflected in the high levels of self-harm - five prisoners had taken their own lives since the jail was last inspected - although all but one were before 2017.
The inspectors found that HMP HUmber was a 'reasonably safe prison - but still not safe enough' and there was 'no doubt the prison was managing considerable risks'.
It also pointed out that it had pursued several initiatives, some more advanced than others, to combat violence and confront drugs. And there was praise for new governor and her team.