Once a week or so, after night falls, about 30 or more young Tunisians set off on foot from the town of Diyar al Hajjaj towards a nearby beach.
They skirt a drying-up lagoon, home to a shrinking flamingo population, and cram on to a small inflatable boat, keeping an eye out for police patrols. Their destination – if they can give the coastguard the slip and survive the dark waters of the Mediterranean – is the Italian island of Pantelleria, about 28 miles away.