The west African nation's most populous jail, located in its economic hub Douala, is crammed with more than four times as many prisoners than its original capacity.
Conditions are dire, even by African standards, and its record is shocking. In June, 16 prisoners were killed while trying to escape from its nightmarish confines.
The majority sleep under open skies due to lack of space in a country with an oppressive tropical climate and pummelled by heavy rain almost throughout the year.
"One cannot imagine what goes on inside," sighed Madeleine Afite from the Christian Action Against Torture (ACAT), a local non-governmental organisation, echoing a sentiment voiced by prisoners and even by jail bigwigs.
Most populous prison
Built in 1935 in the heart of the teeming working-class district, the New Bell penitentiary was originally meant to house a military barracks.
Its filthy yellowing walls are topped by razor wire. There are four rudimentary watch towers and the roads leading to the prison are in a pitiful state.
"It's the country's most populous prison," said New Bell's chief Tsala Amougou, referring to the 3 421 inmates packed into a space originally meant for a maximum of 800.
"The hardened criminals mix with the others freely," deplored Amougou, lamenting that juvenile prisoners left the jail "more delinquent than when they entered it".
Afite said some of the child prisoners were regularly raped by adults.
The prison's head admitted that sanitation was next to nil with an acute shortage of water, open drains and toilets and regular flooding.
"There are innumerable health problems," he said. "Scabies is a recurrent malady."
Every night, the prisoners themselves clear the open pit toilets.
'People are dying everyday'
"In one night alone, I cleared 800 buckets of excrement," said 22-year-old Mathieu, who was jailed for three-and-a-half months for taking part in a demonstration against skyrocketing prices and inflation.
"People are dying every day," he said, underlining that illnesses and physical attacks were exacerbated by extremely poor and inadequate nutrition.
The overcrowding, dilapidated buildings and limited numbers of poorly-paid guards - according to government figures, 23 000 inmates across the country are in the care of 3 000 guards - is not limited to New Bell but all too common in other facilities both in Cameroon and elsewhere in Africa.
The United Nations has repeatedly expressed grave alarm over a litany of "inhuman" conditions in African prisons that it says pose a threat to law and order. It has urged alternatives to confinement, such as community service or other non-custodial measures, while recognising an intractable problem - many states lack of resources to resolve such ills.
At New Bell, the diet is scarce and never changes: a handful of corn and French beans for lunch and some rice - and nothing else - for dinner.
Meanwhile, there is a flourishing racket inside.
"We have to pay for everything: 45 000 CFA francs ($108) for a bunk, 2 500 francs to avoid chores and 100 francs weekly to be able to use the toilet," said Mathieu, terming the prison sheer "hell".
Punched for using the toilet
"I saw a prisoner being punched because he used the toilet without paying."
Mathieu said the warders never intervened whenever a fight broke out among the prisoners. And jail chief Amougou admitted that his hands were tied.
"There are hardly 150 people to man and administer the prison," he said. "There should be 700."
A lack of activity, sexual promiscuity, hunger and high doses of testosterone spark clashes at the drop of a hat, he said.
"We have to relocate the prison," said Amagou, adding that a site had been identified about 20km from Douala but little progress made thus far.
He said the other problem was that petty offenders such as "those with flawed identity cards" were placed cheek by jowl with hardened criminals.
More than 70% of the detainees are defendants awaiting judgement. Some have been waiting for several years for a ruling thanks to the backlog of cases piled up at Cameroonian courts.