Some still try to get through by clinging to the undercarriage of lorries. Others have been found hidden in 'coffins' - plastic containers with tiny air vents - close to death.
Either way, you can be certain of one thing: that when a truck stops on the now notorious Rue des Garennes on the outskirts of Calais, someone will emerge and attempt to get on board. Day or night.
So it was late on Wednesday afternoon when Mail photographer Will Leach trained his lens on an HGV stopping for petrol about 50 yards from his own car. An all-too-familiar scene was unfolding.
Two would-be asylum seekers were climbing into the gap behind the cab and the trailer. You can see them in his dramatic footage. One is in a sweatshirt and tracksuit bottoms and there is a gold ring on his finger. He is no more than 18 or 19. His companion is in a leather jacket and baseball cap.
The time, recorded on the clock on Will's camera, is 18.01. He was unable to capture what happened next on film. For, moments after the picture was taken, the migrant with the gold ring began sprinting towards him armed with a lump of concrete.
'Out of the corner of my eye I saw two other figures rushing out of the bushes so I put the car into gear and my foot down hard on the accelerator,' he says. The first missile shattered the rear windscreen.
The second obliterated a back window on the driver's side, showering 26-year-old Will with shards of glass. A third left a huge dent in the bodywork of the car.
'An occupational hazard' is how he later calmly described being ambushed. Nevertheless, he could have been badly injured or even killed.
The evidence, if any were needed, was inside his car: a lump of concrete the size of two cricket balls.
It smashed into the headrest of the front passenger seat. Had it not been there, it might not have been such a lucky escape.
We had come to Calais to investigate the escalating violence by illegal immigrants after a spate of 'highway robberies' involving British holidaymakers.
Was the violence becoming more indiscriminate, as local reports suggested? At 18.01 on Wednesday we had our answer.
A shanty town of makeshift tents has sprung up in woods bordering Rue des Garennes, where Will Leach came under attack. They call it The Jungle.
The population of mainly refugees from Afghanistan is around 800 - and growing. Conditions and health problems in The Jungle - where fights and feuds between rival factions are commonplace - are akin to the trenches, according to a French doctor who has been there.
But The Jungle - or at least the law of the jungle - has now extended beyond the boundaries of this godforsaken 'community'. Death threats. Assaults. Robberies. This is now the way of things in Rue des Garennes, one of the main routes in and out of the ferry port.
A security guard at an American owned company on the mile-long stretch was clubbed over the head with an iron bar a few weeks ago.
At a nearby truckers' cafe, the owner has had knives pulled on him so many times he is considering pulling out (a number of businesses already have), and at least two British families have been 'carjacked' after being forced to stop by immigrants forming a human chain across the road.
Anyone, it seems - not just journalists who might be perceived as a threat - is fair game. Police have now stepped up patrols. This not just a story spun by the local council's public relations department. We saw the evidence for ourselves.
'This is now routine,' said an officer who was leading up to 20 of his men into The Jungle - from three vans bearing the letters CRS - on Thursday morning. CRS stands for Compagnie Republiquaine de Securite: the elite - and feared - French riot force.
The officers were armed with tear gas, handguns and batons. A 'routine' inspection of the camp takes place at least once a week, every week.
There is a terrible irony at the heart of the so-called 'siege of Calais'. Those are not our words. They belong to the mayor of Calais, Natacha Bouchard. The irony is that migrants are finding it harder to get into Britain through the port because of increased security on both sides of the Channel.
Yet the number trying to reach the UK has increased, to more than 2,000 a month - a figure that has doubled over the past year. The desperation behind these statistics can be found in three adjoining houses on the edge of Quai de La Moselle, a vast open space in the middle of Calais. Around 50 men and women from Eritrea and other African countries have turned the properties into a squat.
Outside, in a walled yard, one of the residents, a 25-year-old from Kenya, picks up a four-inch metal bolt that is attached to coat-hanger wire. Every month, he says, he heats up the bolt and then, one by one, touches the scolding metal with his fingertips, which doesn't cause major scarring, but alters the texture and appearance of the skin.
It's an excruciatingly painful but effective way, he explains, of removing your fingerprints. 'I have to do this regularly because your prints can grow back,' he says.
Migrants can be deported if fingerprint checks reveal they have lodged asylum applications elsewhere. No fingerprints, no deportation; instead the opportunity to stay in Calais, from where you can try to enter Britain.
Already the young Kenyan has made 30 such attempts in the six months since he arrived. He said that four others in the squat have also burned off their fingerprints.
His claims would be hard to believe had the phenomenon not been confirmed by the authorities here. At least 57 asylum seekers questioned in the port over the past few weeks have had their fingerprints - and sometimes even the tips of their fingers - erased. Most placed their fingers on a heated oven hob. Knife and razor scars were also commonplace.
The kind of people who are prepared to mutilate themselves to conceal their identities will do almost anything. It is a situation that is being exploited more than ever by people traffickers.
When we entered The Jungle on Rue des Garennes earlier this week such people, we were told, were not in the camp. They were back in Pakistan and Afghanistan, but not here. The police tell a different story.
A single raid by the CRS in April resulted in 194 arrests of suspected people traffickers. In other words, nearly a quarter of those living in this sprawling cardboard and tarpaulin city had possible criminal links.
It is extremely difficult to build a case strong enough to put before the courts. So almost all of them had to be released. 'Technically, we can return them to the country they arrived from,' said a police source. 'They usually say Belgium but if we take them there they just come straight back again.'
Good for Belgium. Not so good for Calais, which is bearing the brunt of an international crisis that is having a disastrous effect on tourism and business in the town.
Many of the migrants here are children, and you'd have to have a hard heart not to feel some sympathy for a 14-year-old boy like Dil Khan, whose family handed him over - blindfolded - to a gang they paid to smuggle him out of wartorn Afghanistan. They wanted to give him the chance of a better life; instead, he now shares a hovel with another poor wretch.
Or 16-year-old Jan Jamal, who lost four fingers on his left hand in a bomb blast in the same country. Jamal repeatedly pointed to the boot of our car when we spoke to him and a friend in Rue des Garennes. 'We can fit. We can fit,' he kept saying. What he meant was: 'Please take us with you.'
Pitiful stories. Equally tragic examples of forgotten youngsters were standing in the long, winding queue for the twice-daily soup kitchen in Quai de La Moselle near the squat where the young Kenyan we spoke to scratches out an existence.
But you do not have to be in Calais long to realise this is not the whole picture. Not today, anyway. Many of the 'poverty-stricken' migrants have mobile phones and new clothes.
It's no mystery. At the Hotel de Poste - the local post office - in Place De Reims in the town centre, the woman in charge reveals how some of her most regular customers are asylum seekers.
The branch is small, no bigger than a corner shop. Yet every day migrants come in to collect money, transferred to them via the Western Union bank, from relatives overseas, including many in Britain. The payments are made out in cash with the production of a valid ID.
Most migrants have papers to meet this requirement. The branch itself handles about 45 such transactions a day. The average is 500 euros (£430). 'It's a massive amount for a small post office,' said the manageress.
Once upon a time, Calais used to be synonymous with shopping trips to stock up on duty-free food and drink for Christmas. But a spokesman for the mayor's office admitted: 'Calais is now blighted as a place to do business, and as a place to live.'
The problems facing the town, it is claimed, are reminiscent of the 'worst days of Sangatte'. The Red Cross Centre at the village outside Calais was shut down in 2002 over its role as a magnet for would-be illegal immigrants.
Five years on and many in Calais, including the mayor herself, blame Britain for what is happening. If Britain were not perceived as 'El Dorado', they say, there would be fewer migrants. She has a point.
A meeting, attended by French immigration minister Eric Besson, was held at the Tioxide factory a few weeks ago to listen to the views of those who work and live near the Rue des Garennes.
Just days earlier, a nightwatchman evicted two residents from The Jungle who had broken into the plant. For months, small groups had been getting in to use the shower facilities and to charge their mobile phones. On this occasion, the two young men decided to come back.
They found the guard and smashed him over the head with a metal bar. Had he not been wearing a helmet, Philippe Ficquoy might not be turning up for duty today.
Other staff, we learned, have also been attacked over the past few months, and have received death threats. Some local businessmen have already thrown in the towel.
One moved his caravan showroom out of Calais after experiencing intimidation and break-ins. Another who owned a yard selling second-hand pallets has closed altogether.
Then last week, two British families found their cars surrounded by migrants. In the first carjacking, the male driver was forced to throw his wallet out of the window after having a knife waved in his face.
Among those who was at the meeting with Mr Besson was Chris Wood, 63, who set up his business, Eurostop, selling beer and wine 20 years ago. His offices and warehouses are the closest buildings to The Jungle. He said his profits are down 50 per cent because of the problems in Rue des Garennes.
'A lot of lorry drivers are now too nervous to stop here because they know as soon as they get out of their cabs people from the camp will try to get in the back, and when they are challenged they can get very nasty,' said Mr Wood, who has a French wife and three children.
Mr Wood himself has been threatened with iron bars and cut-throat gestures. 'The police are doing the best they can,' he said. 'But I think the situation is now out of control.'
The closure of the Red Cross centre was supposed to help relieve the pressure on Calais by discouraging migrants from coming to this area. In fact, almost the complete opposite is true, and no one on either side of the Channel seems even remotely close to finding a solution.
For the thousands of British families who will run the gauntlet of these lawless streets in their cars this summer, it is a chilling prospect.
