In the middle of an industrial estate in Zaandam, just north of Amsterdam, stands the newest prison in the Netherlands.
But the word "stands" is not quite right, because this prison is in fact moored on one of the country's many waterways.
And the inmates in this floating prison are not criminals but illegal immigrants, guilty of what the Dutch call an "administrative offence".
This is the answer to a problem the authorities faced in the late 1990s - how to separate illegal immigrants from ordinary criminals when you already have overcrowded prisons.
"It's easier to get a place on the water than to find land, plus it's easy to build," says Erik Nijman from the Dutch ministry of justice.
And he says a floating prison is also more flexible: "If we have a problem for example in Amsterdam, we can transport them over water."
'No easy option'
Built by the side of an old wood yard, the prison sits on two concrete platforms, each in turn moored to large steel pilings.
On dry land next door are two white domes specially designed by a Dutch artist. Made of a lattice-work of metal, this is where the inmates play sports like football or basketball.
To enter the prison, you walk across a small bridge. Inside the corridors of cells are bright and clean. There are communal areas with table football, table-tennis and payphones.
The cells themselves hold two people, with bunk beds, a desk, fridge, TV, even a coffee machine. An en-suite bathroom is fitted with a toilet and shower.
When the prison is full it will house 576 illegal immigrants.
But despite state-of-the-art facilities, this is no easy option.
Cells are locked for 15 hours a day, from 1700 to 0800. Inmates can stay for six months or longer, as the authorities try to identify them and persuade them to go home voluntarily.