A World War I fort in the middle of the Humber estuary could form the next frontline in the war against drugs.
The fort stands on an island of concrete built in 1915
Bull Sands Fort stands on an island of concrete built in 1915 to protect the mouth of the Humber from German attack.
The drugs charity Streetwise is working to transform it into an offshore detox "sanctuary" where hardened users can be isolated from their dealers.
Streetwise trustee Philip Ball said: "It may look like Alcatraz but to them it's an island of hope."
Largest in world
Standing 18m above the tidal waters with a 25m diameter, the imposing concrete structure provided accommodation for about 200 soldiers during both world wars.
Streetwise bought the Bull Sand fortress nine years ago and has planning consent to transform it into a residential centre providing a free, on-demand, 30-day detox programme.
The charity says it would be capable of accommodating 240 addicts every month - the largest facility of its kind in the world.
Mr Ball said that accommodating drug addicts on a man-made island sounded drastic, but was necessary to help those who had long-term habits.
"We are talking about people who know they are coming to the end of their lives, they know it is their time.
"When they come to us they will be in pretty dire need, they may be in need of a place of safety, a sanctuary.
"We want the service to be free of charge and on demand, a bit like a hospital's accident and emergency department but for those with narcotic and alcohol problems."
Mr Ball and a team of volunteers have spent the last five years preparing the once-derelict site for habitation.
The RAF has provided helicopters to lower generators onto the island to power the tools needed to convert the building.
Fresh water will be pumped up from an artesian well below the estuary bed, as it was when soldiers occupied the site during World War II.
But Streetwise does not have enough funding to launch the project as a going concern.
"There are no problems out there that money could not resolve," said Mr Ball.
"If we had £1m the place would be up and running within six months."
The organisation has appealed unsuccessfully for financial help from the British government and other agencies and is now looking further afield for aid.